1. By: Stephanie Bales, Kelley Fox, and Courtney Dunford
Composition of Soil
By: Stephanie Bales, Kelley Fox, and Courtney Dunford

2. Soil comes from rocks, minerals, and organic materials
Components of soil: mineral matter, air, water, organic matter
Cause of soil erosion: water, wind, no vegetation

3. Words To Know
Clay: fine grain soil that is pliable when moist but hardens as it is heated
Compost: decomposed organic material
Loam: a soil containing clay, sand, silt and organic matter
Metric system: a system of measurement based on powers of ten
Sand: loose particles of broken rock
Silt: particles of rock slightly larger than clay but smaller than sand
Topsoil: upper layer of soil, plant roots are typically found here

4. Rock Material Stone, sand, silt and clay Comes from “parent rock”
Parent rock determines the chemical back bone of the soil
It also determines the grain size
Topography, time and climate effect composition and the breakdown of the rock
It may appear as pebbles, gravel, or as small as particles of sand or clay.

5. Organic Material
Plants, animals, fungi, bacteria and humans affect the composition of the soil
Decaying of once-living organisms (plants or insects)
Fungi and bacteria affect the exchange of nutrients between plants and soil
Humans remove vegetation which causes erosion.
This is plants or animals that have died and decayed until they become part of the soil.

6. The amount of water in the soil is closely linked with the climate and other characteristics of the region. The amount of water in the soil is one thing that can affect the amount of air. Very wet soil like you would find in a wetland probably has very little air. The composition of the soil affects the plants and therefore the animals that can live there.

7. Layers of Soil
Defined by color, size, texture, structure, consistency, root quantity, ph and other factors

8. 5 Layers Top Layer – “O” – Organic
Found in forest soils
Made of dead leaves and debris
2nd Layer – “A” – Organic Material is mixed with Inorganic Material
Usually darker, and if it’s tere means the soil is fertile for plants
3rd Layer – “E” – result of acidic water running through 1st 2 layers
4th Layer – “B” – Minerals an clay grains accumlte here – can be thick and tight – difficult for water to penetrate
5th layer – “C” – contains the parent inorganic material (rock)
If there wasn’t soil there wouldn’t be plant life on the surface of the land

9. Stages in the Formation of Soil