Soil Orders Study Guide – Part I

1. Soil Orders Study Guide – Part I These slides are to help organize in your mind: • Key diagnostic features for each Soil Order • Their developmental progression • Diagnostic surface & subsurface layers See also – for the individual orders: • the text’s description and plates • Soil Orders Study Guide – Part II (on course website)

2. Soil Orders: Key Formative Factors • Note their: • Relative order • Key formation factors

3. Processes Leading to Diagnostic Surface Layers (Epipedons) See text for full descriptions

4. Processes Leading to Diagnostic Subsurface Layers Albic Light colored horizon Argillic Weakly developed horizon Cambic High clay content Clay skins evident No significant accumulation silicate clays Accumulation of Extreme weathering Fe, Al oxides Oxic Unweatheredmaterial Accumulation of organic matter Acid weathering, Fe, Al oxides Spodic Accumulation of inorganic salts Carbonates primarily CaCO3 Calcic Modified from text: full version = Figure 3.5 (p. 83) See text for full descriptions

5. Diagnostic Key to Soil Orders In addition, see the text’s version: Figure 3.11 (p. 90)! Missing: Andisols, Gelisols

6. Development of soil orders

7. Bk ice Bo Development of soil orders A AB Bh Bs Bt Hi Base Sat Hi pH Lo Base Sat Lo pH Missing: Inceptisols, Andisols, Vertisols, Histosols These are plausible, but not the only genetic profile descriptions that are possible for each soil order

8. Effect of time on soil development