2. Soil and Natural Vegetation Physical Geography

3. Do We Really Need Soil? Let’s Dig Up the Facts!

4. Soil Contains the Minerals All Living Things Need!

5. We Use Soil to Grow Food!

6. Many Animals and Microscopic Creatures Live in the Soil!

7. Soil Helps Soak Up Rainwater So We Don’t Have Flooding!

8. Soil Soil is made up of 4 main parts: Minerals Organic and Bacterial materials Moisture Air Think -MOMA

9. Minerals Ex. calcium, phosphorus, potassium, etc.. Comes from parent material (usually rock) or loose material deposited from a glacier Minerals become part of the soil when rock is broken down by weathering

10. Organic and Bacterial Material Dead plants and animals are decomposed by bacteria in soil, nutrients are released to form humus Humus provides nutrients and moisture to plants and gives soil its dark colour.

11. Moisture Water dissolves nutrients in soil allowing plants to take them up through their roots Water is also needed in the processes that weathers rock and decays organic material

12. Air Air in soil is created by high humus levels (loose, decaying material allows for many air pockets), worms, insects and small animals Plants need air around roots

13. Typical Soil Profile

15.  Horizon O  Leaf litter, organic material  Horizon A  Top Soil  Rich in organic materials  Dark brown or black in colour  Horizon B  Sub Soil  Combined mineral and organic layer  Lighter brown in colour  Horizon C  Parent Material  Mineral materials  Usually bedrock or glacier deposits

16. What happens if the soil is too wet? Leaching- the excess water dissolves nutrients and carries them away (downward), making it difficult for plant roots to reach nutrients Leached soil has poor, usually thin topsoil layer Much of Canada is covered with Wet-Climate soil

17. What if the soil is too dry? Calcification- there is an upward movement of water As water in the top soil evaporates, water from below is drawn up to replace it As water evaporates, it leaves behind minerals Topsoil is thick and rich in minerals If soil is very dry, the amount of minerals left can create a layer that is poisonous to plants