Soil Profile and
Worm Observation Chamber
Nov. 15, 1993
O Horizon - Organic Horizon
2 inch. Compost
Compost is partially decomposed organic matter such as leaves, garden
residue, and food waste. In its active state, compost contains millions
of microorganisms and other soil-dwelling organisms which consume the
ever changing organic matter and each other.
Artificial Layer -
1 inch. fine white sand (to use as a marker)
The artificial layer is not found in a natural soil profile. It serves
as a marker to help with your observations.
A Horizon -
3 inch. Topsoil
Healthy topsoil teams with life. Plant roots, bacteria, fungi and small
animals make topsoil a living system. Because it has more organic
matter, topsoil is darker than subsoil.
B Horizon -
4 inch. Subsoil
Subsoil, may be brown, red, yellow, or gray. It may be quite sandy. If
made up of clay, it will be hard when dry, and stickier when wet than
surrounding soil layers. This middle soil layer contains few organisms,
but plant roots may penetrate into it.
C Horizon -
1 inch. small rocks, 1-2 inches in diameter
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