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Soil and Natural Vegetation. Physical Geography. Soil. Soil is made up of 4 main parts: Minerals Organic and Bacterial materials Moisture Air Think -MOMA . Minerals. Comes from parent material (usually rock) or loose material deposited from a glacier
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Soil and Natural Vegetation Physical Geography
Soil • Soil is made up of 4 main parts: • Minerals • Organic and Bacterial materials • Moisture • Air • Think -MOMA
Minerals • 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
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.
Moisture • Water dissolves nutrients in soil allowing plants to take them up through their roots • Water is also needed in the processes that weather rock and decay organic material
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
Typical Soil Profile • Horizon O • Leaf litter, organic material (grass) • 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
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
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
Natural Vegetation Regions • Draw a cross section of a typical soil sample in your notes (copy from page 147- fig 13-2) • Color a map showing the Soil Regions of Canada(figure 13-1, page 146)