Soil We cant live without it Need fertile

Soil

We can’t live without it • Need fertile soil to grow plants • Animals need plants to live • There isn’t a lot of fertile soil on Earth

What is in soil?

Where does soil come from? • All soil starts from rock. • Rock weathers (breaks down) into very small pieces to form soil • Two types of weathering – Chemical weathering – Physical weathering

Chemical and Mechanical Weathering • http: //www. brainpop. com/science/weather/ weathering/

Weathered Rock • Weathered rock doesn’t stay put, but is usually moved by erosion • Erosion can happen from wind water ice

Erosion • http: //www. brainpop. com/science/earthsys tem/erosion/

Soil Color • Two sources of color in soils 1. Minerals in the soil Mica is dark Quartz is light Hematite is red

Soil Color, continued 2. Organic material = darker the soil • More fertile • Comes from dead plants and animals. Organic material in soil is called humus.

Soil Particle Sizes/Texture • Sand—smaller than gravel, water flows through easily, feels gritty • Silt—smaller than sand, water has a harder time flowing through, feels soft (like powder) • Clay—smaller than silt, water usually doesn’t flow through, feels sticky

Soil p. H • p. H measures how acidic or basic something is –Usually ranges from 0 to 14 –Low number = acidic (lemon juice=2) –High number = basic (baking soda=9) – 7 = neutral (water)

What happens if something is missing from the soil? Missing water = Dry Soil Missing organic material = Poor Soil Missing Air = Compacted Soil

Fertile Soil • Dark in color = high nutrients and organic matter • Not too dry or wet • p. H between 6 -7 • Temperature between 65 o. F and 75 o. F • Balance of sand, clay, and silt • Thick layer of topsoil