| Home | Calendar | Course Outline | Announcements | Syllabus | Study Aids | Grades | Geog/Geol Dept | UWSP |

SOIL CHARACTERISTICS

A. Introduction

• unconsolidated mineral and organic matter mixed with liquids and gasses
  

• occurs naturally on the earth's surface and is a medium capable of supporting growth of rooted plants
  

• differs substantially from the material from which it is derived
  

• characteristics: used to distinguish one soil from another or one layer in a soil from another layer

---

B. COMPOSITION

Inorganic material Organic material Water Air

---

C. COLOR

Image credit for both soil photos: U.S. Department of Agriculture, NRCS, Distribution Maps of Dominant Soil Orders http://soils.usda.gov/technical/classification/orders/

Black: high organic content

Yellow/red/orange: iron

Light gray-white: calcium or silica

---

D. TEXTURE

• Percent clay, silt and sand

clay <0.002 mm

silt 0.002-0.05 mm

sand 0.05-2.0 mm

• Texture triangle   

---

E. STRUCTURE

Designates shape, size & organization of peds

platy: horizontal, flat, plate-like peds	prismatic & columnar: long, vertical peds bounded by flat to slightly rounded vertical faces
blocky: squarish block-like peds	granular: small rounded peds

Image credit for all four structure photos: U.S. Department of Agriculture, NRCS Soil Survey Manual, Chapter 3 part 7 http://soils.usda.gov/technical/manual/contents/chapter3g.html

---

G. ORGANIC MATTER

• Litter

• Humus

---

H. CHEMISTRY

• Cation exchange capacity

  • cations: positively charged particles

  • important nutrients    

Na: sodium

Ca: calcium

Mg: magnesium

K: potassium

 

• Acidity/alkalinity

---

I. SUMMARY

• Composition

• Color

• Texture

• Structure

• Soil water

• Organic matter

• Chemistry