2. The material covers the
earth’s surface in a thin
layer.
Any part of the earth’s
surface that supports
vegetation also bear a
covering of soil.
3. Soil contains four main
components: inorganic
material, organic matter,
water, and air.
4.
5. It is the vertical section
through the soil and
extending into the
unweathered parent
materials and exposing
all the horizons.
6.
7. The O Horizon-
Is the organic layer made of
wholly or partially decayed plant
material and animal debris . You
can normally find this layer in a
forest with fallen leaves,
branches and other debris.
Horizons
8. A horizon has a dark brown colour as humus
replaces minerals as they are leached out.
Leaching however is less pronounced here.
B horizon is less pronounced in colour
because humus becomes less abundant here.
C Horizon is derived from varied parent
material.
Mixing of horizons due to presence of soil
biota.
Tree roots reach deep into the soil to allow
any leached chemicals to be brought back up
into the leaves.
9. The horizons may be further
subdivided.
For example, in this soil
profile the A horizon has been
divided into 4 further
pedological horizons:
• (L) leaf litter
• (F) fermenting leaf litter
• (H) humus
• (E) eluvial
These lie above the (B) or
illuvial horizon.
Fresh vegetation
Dead vegetation-Litter (L)
Fermenting litter (F)
Humus (H)
Eluvial horizon (E)
Illuvial horizon (B)
Soil Horizons
Ahorizon
