1. 1 Soils Soil is made up of a number of different layers.

2. 2 Different Layers of Soil Upper layer (O) known as litter Topsoil layer (A) contains humus Subsoil layer (B) stones mixed with some humus Bedrock (C)

3. 3 Layers of Soil Litter Layer Topsoil Layer Subsoil Layer Bedrock

4. 4 Layers of Soil Litter Area on top of soil contains leaves, dead plants and organisms. Reduces water loss Limits changes in temperature

5. 5 Layers of Soil Topsoil Humus Layer….Plants and decaying animal matter Roots of plants Small particles of rock Darker in color

6. 6 Layers of Soil Subsoil More rocks than topsoil Less humus than topsoil Lighter in color

7. 7 Layers of Soil Bedrock Solid rock found beneath subsoil Can be seen at the surface if other layers are washed away

8. 8 Groundwater Versus Surface Water Groundwater …water which moves down through the soil. Surface water... water which runs on the ground and collects in lakes, ponds and oceans

9. 9 Percolation Process which happens when surface water is pulled downward by gravity to form ground water.

10. 10 Leaching Occurs when water dissolves and takes nutrients from the soils. Occurs during percolation Takes nutrients from plants leaving soils more infertile

11. 11 pH of Soils Soils can be acidic (pH less than 7) Soils can be basic (pH greater than 7) Soils can be neutral

12. 12 Factors affecting pH of soils Type of rock Alkaline minerals in rocks can cause high pH’s

13. 13 Factors affecting pH of soils Type of Plants Decaying plants can cause soils to have lower pH levels and become acidic.

14. 14 Factors affecting pH of soils Burning of fossil fuels When acid rain enters the soil it lowers pH. Takes nutrients from the topsoil.