Soil
• Soil is made of
• A. weathered rock/
sediments
• B. humus- decayed
plant and animal
matter
• C- living organisms(worms, fungi and
insects)
Soil Horizons- layers of the soil
• 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.
• 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.
• 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
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Parent materialType of vegetation- see next slide
Slope of the land
Climate
Time
Notice the thicker darker top layer
at the bottom of the slope