Do Now:
•Read the Short story from John Muir, then answer the following questions:
•1. Why is soil an important part of our environment? T and T
•2. What are ways soil can be weathered?
I. Soil is more than just dirt.
Complex, ancient material teeming with living organismsCategorized by physical & chemical features
color & texture How does soil form?
2. Chemical weathering
Result of chemical interactions between water, minerals in the rock and other atmospheric gases.
Evacuated ocean front homes from cliffside erosion & heavy rains due to "El Nino" in 1998. What type of erosion is this?
B. Soil Texture Categories by U.S. Dept. of Agriculture (USDA)
Clay- particles < 0.002mm in diameterEasily sticks together, really compactedLittle pores so it can hold little water
Soil Textures Continued:
Silt- particles 0.002 - 0.05 mm in d
Sand- particles 0.05 - 2.0 mm in dToo large to easily stick, looseLarge pores so it can hold more water
C. Soil Acidity & AlkalinitypH range= #0-14Tells you the [] of hydrogen ions
Soils pH is usually between 4-8 Neutral/slightly acidic
Acidity: How acidic the soil is.pH = 0-6
Alkalinity: How basic the soil ispH = 8-14
1. pH affect on soil
pH affects solubility of nutrientsDetermines the nutrients available for absorption by plant rootsIf too acidic/basic, certain soil nutrients will not be able to be used by regional plants