Soils

Soils Soil is the loose covering of broken rock particles and decaying organic matter Soil is the end result of physical and chemical weathering. Soil forms as rock is broken down be weathering and mixes with other material on the surface. The longer a soil has been forming, the thicker it is. Climate has a great affect on soil formation. Temperature and precipitation play an important role.

How is soil created? Decaying organic matter is called humus. It is often leaf litter that is broken down by decomposers. Ex. Are ants, worms, etc.

Soil Formation During its development, soil forms in layers vertically. Solid bedrock from which weathered pieces of rock first break off is known as the parent rock. The weathered material then rests on top of the parent rock.

Residual vs. Transported Residual soil is soil that comes from the bedrock that it sits upon. A transported soil is soil that has been moved from a different location

Soil Profile A soil profile is a vertical sequence of soil layers. A distinct layer is called a soil horizon The three major layers are: A, B, C

Soil Horizons A Horizon- Topsoil- Soil rich in humus and usually dark colored B Horizon- Subsoil-Rich in clay minerals C Horizon- Weathered bedrock (parent rock).

Texture Size of soil particles is soil texture. Particles are classified according to size. In order from largest to smallest they are: Gravel Sand is the largest .05- 2 mm Silt is the middle .0002 - .05 mm Clay is smallest >.002 mm

Fertility and Color Soil Fertility is the measure of how well a soil can support plant growth. A soils’composition and climate are main factors in determining its color. Red/Yellow= Fe oxidation Dark Colored= Humus Gray/Blue= low O2

Loam A loam is a soil that is equal parts of clay, sand and silt. It is the best for growing plants!

Soil Types Climactic conditions are the main influences on soil development. Polar Soil Temperate Soil Desert Soil Tropical Soil