1. Unit 5: Biosphere Ms. Thind SOIL FORMATION AND SOIL PROFILES

2. 1.Decaying vegetation:  In areas of favorable climate for vegetation growth  Decaying organic matter is broken down  dark, sticky partly decomposed layer at soil surface  humus  Very fertile  Ideal for agriculture FORMATION OF SOIL

3. 2. Leaching:  Layer of weathered rock particles and decaying organic matter allow water to pass through  dissolved minerals are carried deep into rock particles  process of water soluble minerals transported through the soil  Tropical wet climate

4. 3. Capillary action:  Occurs in dry desert and grassland regions  Surface layers so dry that water is transferred deep in the ground to the surface  Capillary action brings water and dissolved minerals close to the surface  Very fertile

5. 4. Translocation  Movement of solid material from one place to another  Transport of material occurs on the surface or downward through the soil and carried by water  Soil animals play a role eg: worms, burrowing animals

6. Soil layers or soil profile begin to appear form: weathering organic debris parent material  Soil that forms in areas with rainfall and vegetation have distinct soil layers  horizons FORMATION OF A SOIL PROFILE

7. A-horizon: topsoil layer, darker = more humus = more fertile B- horizon: subsoil, brown/red  clay and iron oxide through translocation. In areas of heavy precipitation. Excessive leaching  transports soluble materials into bottom layers. C-horizon: rock partially weathered, above parent material or bedrock. SOIL PROFILE: 3 HORIZONS

8. 5 main soil types: 1.Chernozem soils 2.Podzol soils 3.Laterite soils 4.Sierozem soils 5.Tundra soils SOIL TYPES

9.  Temperate prairie grasslands  “breadbasket” areas of the world  North America Prairies, Russian Steppe  Very fertile  thick, dark humus layer  Dry summers  leaching not a problem  capillary action brings nutrients to the surface  Cold winters  freezes soil  burrowing animals important to mix up soil CHERNOZEM SOILS

10.  Topical low pressure belt  Very deep and red due to high iron oxide content  Leaf litter adds nutrients to soil  Trees have shallow root system to capture nutrients in top layer  Infertile soil LATERITE SOILS

11.  Coniferous forests  Humid Continental  cold winters, warm summers (due to lack of ocean influence)  Heavily leached and very acidic  Thin humus layer of decaying evergreen needles PODZOL SOILS

12.  Desert soils  areas of little precipitation  Limited vegetation  Organic content is low  Little rainfall = poorly defined soil layers  Can be fertile when irrigated  stirring the soil  capillary action brings nutrients to surface layer SIEROZEM SOILS

13.  Permafrost limits the circulation of water in soil = layers not well defined  Low temperatures  decomposition of vegetation is slow  small decomposing organic layer TUNDRA SOILS