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

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

4. Argillic Oxic Calcic Albic Cambic Spodic Unweathered material Light colored horizon Weakly developed horizon Acid weathering, Fe, Al oxides Accumulation of organic matter Accumulation of silicate clays High clay content Clay skins evident Extreme weathering Fe, Al oxides Accumulation of inorganic salts Carbonates primarily CaCO 3 No significant accumulation Modified from text: full version = Figure 3.5 (p. 83) See text for full descriptions Processes Leading to Diagnostic Subsurface Layers

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

6. Development of soil orders

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

8. Effect of time on soil development