Typical Soil Profile

O Horizon

• The O horizon is the top layer and contains the most recent decaying matter. It is loosely compacted, with a majority of it being rich humus. The nutrients from this layer leach down into the lower soil layers. The O horizon is thick in rain forests and areas where there is a high amount of falling debris.

A Horizon

• The A horizon is known as top soil, because it is considered the start of the true soil. It is a dark-colored soil, due to its high organic matter content. This is the main soil level of fields and plains.

E Horizon

• The E horizon can be found directly below the O or the A horizons. It is light in color because of its high level of leaching, which leads to a lack of nutrients.

B Horizon

• The B horizon, or the subsoil, is where downward-leaching particles come to rest. It is highly compacted due to the weight of the upper layers. It often consists of a high clay content.

C Horizon

• The C horizon consists of weathered and broken rock particles. It has minimal nutrients and consists mainly of the fractured pieces of the parent rock beneath. The layer below the C horizon is known as the bedrock.