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Soil

is made of • A. weathered rock/ sediments • B. humus- decayed plant and animal matter • C- living organisms (worms, fungi and insects) Soil

Soil Horizons- layers of the soil

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A horizon-

also called topsoil is made up of dead and decaying plants and animals. This layer is dark in color and rich in nutrients that are used by plants.

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B horizon-

this layer is lighter in color because there is not any humus. Minerals are washed downward from the A horizon into this layer by a process called leaching.

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C horizon

– this layer is the parent material containing mostly weathered rock or sediment

Soil profiles

side view of the different horizons (layers ) of soil in the ground.

Factors that affect soil formation

• Parent material • Type of vegetation- see next slide • Slope of the land • Climate • Time

Notice the thicker darker top layer at the bottom of the slope