1. Soil Defined as the part of dirt that will support life
Found in all places all over the world, but not all soil is the same
Oceans and deserts have sandy soil, swamps are muddy soil
Soil is divided into four parts
Water  Found in pore spaces and supplies the moisture and nutrients for root systems
Air  Found in pore spaces and is a source of carbon dioxide and oxygen for plants and animals
Mineral Matter All the sediments that make up most of the soil
Organic Matter  Humus is the decayed matter from dead animals and plants that supplies nutrients to soils

2. Soil

3. Soil Formation Soil is made from the weathering and erosion of rocks
Five factors that determine the soil types
1. Climate (most important factor)
Warmer and wetter climates that encourage all types of weathering will have some of the thickest soils
Drier, cooler climates will have thinner, not good soils
2. Parent Material
The sediments in the soil have to come from an original rock that got weathered called a parent rock
The harder the parent rock, the less sediments you have in the soil because not many rocks will weather easily

4. 3. Time
The longer the time you have to weather the rocks, the thicker the soil that you will have.
4. Organisms
Plants are the mains source of organic humus in the soils
Microorganisms and fungi will decompose the dead stuff into nutrients that animals and plants can use

5. 5. Slope
On steeper slopes, erosion will increase, very little water gets into the soil, and the soil itself is very thin because much of it will be pulled down by gravity
Flatter areas will have erosion decrease, lots of water in the soil, and the soil is generally thicker

6. Soil Profile
Soil is not the same all the way down to the crust, it changes as you go further down
The layers of soil are called the soil profile
There are four layers to the soil profile
A-Horizon, B-Horizon, C-Horizon, and the Unweathered Parent Material (UPM) also known as the crust of the Earth

8. O-Horizon
This extremely thin layer is the pure organic layer of the soil profile
This layer is made of humus, the dead leaves and organic bodies of the organisms that live there

9. A-Horizon
Top layer of the soil that contains most of the nutrients for the plant’s roots
Many roots, bugs, and burrowing animals will be in this layer
Mostly made of humus, water and air

10. B-Horizon Mostly made of clay and water
Not much air makes it down here because the pore spaces filled with water that trickled down
Deeper roots reach down from older trees to get the water found there
Not many bugs or smaller creatures here because the clay is so hard packed that they cannot dig through

11. C-Horizon
Mostly made of weathered parent material (smaller to larger sediments)
Only the deepest roots will reach down here for the water that is there
Few if any animals or bugs because they cannot dig through the rocks

12. Unweathered Parent Material (UPM)
This should be solid bedrock to some weathering towards the top of the layer.
No animals are here because there is no air and very little water

13. Soil Textures
Refers to the proportions of the different particles sizes that are found in all soils
Categories are based on the percentages of sand, silt and clay
The different textures can be found on a diagram called the soil triangle