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
• 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