1. 5.2 Soil

2. Soil -Product of weathering -one of our most important resources *Regolith- layer of rock and mineral fragments that nearly everywhere covers Earth’s surface -supports and regrows plants

3. 3 Characteristics of Soil 1.Composition 2.Texture 3.Structure

4. Composition -mineral matter/broken down rock -organic matter/humus/decayed remains -water -air *Bogs-mostly organic material *Deserts-only a tiny bit of organic material

5. *organic matter/humus-important source of plant material *water-moisture needed for chemical reactions *air-source of carbon dioxide for photosynthesis in plants

6. Soil Texture-size of particles -determines how easily soil can be cultivated and susceptibility to erosion

7. Soil Formation -parent material- source of mineral matter -time-longer forming= thicker soil (top soil) -*Climate-greatest effect on soil formation -organisms-impact on physical and chemical properties. Types of plants, animals, decayed matter, etc -Slope-steep slopes- more erosion

8. *Soil varies in composition, texture, structure, and color at different levels. *Soil Profile-vertical section through a soil showing its succession of horizons and underlying parent material *A Horizon-top soil- organic matter *B Horizon-subsoil (fine clay)- lower limit for most plant roots & burrowing animals *C Horizon- unaltered parent material

9. Soil types 1. *Pedalfer- soil of humid regions; iron oxides & aluminum rich clay 2. *Pedocal- soil of drier regions; calcuim carbonate 3. *Laterite- red, highly leached soil found in tropics; iron oxides and aluminum

10. Laterite (continued) -ancient structures made of this are still well preserved -clearing of rainforests- soil becomes hard, infertile, red, eroded ground once a few growing seasons are over

11. *Soil Erosion-soil moved by water, wind, glaciers, etc. *Sheet erosion- caused by water flowing over a surface

12. Rates of Erosion -Human activities that remove natural vegetation, such as farming, lodging, and construction, have greatly accelerated erosion -Depends of climate, slope, and type of vegetation