1. Soil
Soil is a mixture of weathered rock, organic matter, water, and air that is capable of supporting plant life.

2. Soil
Soil originates from weathering of the bedrock beneath it or from materials transported from another location.

3. Soil
Soil Horizons
The figure shows a complete set of horizons, designated as O, A, E, B, C, and R from the surface to bedrock.
The O horizon, for organic, and the A horizon often are referred to as topsoil.

4. Soil Horizons
The E horizon is a zone in which finer sediments and soluble materials are transported downward.
The B horizon collects the materials from above and is usually darker than the E horizon.

5. Soil Horizons
The C horizon is partially crumbled and weathered bedrock. The R horizon is unweathered bedrock.

6. Soil Types
Climate often is used as a basis to characterize many different types of soil.

7. Soil Types
They are separated according to composition and physical properties.

8. 1
Soil Types
The amount of precipitation and the temperature range of a region, together with the type of parent material, affect the type of soil that is formed.

9. Weathering and Soil 1
Soil Conservation
Soil depletion is a serious agricultural problem in many regions.

10. 1
Soil Conservation
Soil depletion is most often corrected by the addition of fertilizers containing nitrogen, phosphorous, or potassium.

11. 1
Soil Conservation
Most soil lost to erosion occurs because the vegetative cover has been removed or because the land is overly steep.