Soil Profile and Horizons Explained
Soil is all around us Soil is essential. You walk on grass rooted in the soil and eat food grown in soil.
Plants and trees need soil to grow but
What is soil composed of
If you look at a chart of soil you will see that Soil is made up of,
45% minerals
5% organic matter like decaying plants and animals
25% water
24% air
You can also study soil by looking at the soil profile and the soil horizon
A vertical layer of soil that shows all of the different layers is the soil profile.
Much like your profile on Facebook tells others all about you The profile tells others all about the soil
A soil horizon is each individual layer of the profile. Each layer has different physical properties.
Learn the difference between soil profile and the soil horizons.
The soil horizons are the horizontal layers of the soil. The layers are o a e b c r.
O horizon also called litter is composed of dead leaves, twigs, sticks, fallen trees The O horizon is thin in some soils, thick in others, and not present at all in others.
A horizon also called topsoil Contains rich organic matter along with some minerals. This layer contains decomposers. The decomposers perform the task of breaking down plants and animals. The remains of these plants and animals create a mixture called humus which is a dark, organic material that forms in soil when plant and animal matter decays.
E horizon also is known as the Eluviated layer as water moves down the soil substances are removed and pulled out in this layer resulting in a concentration of sand and silt particles composed of quartz or other resistant materials This layer may be missing in some soils.
B horizon Subsoil Lighter in color, many times reddish or brownish in color because it has less humus it is a zone of accumulation where materials like clay collects from the movement of water downward
C horizon Parent material this layer contains much of the material that the soil was originally made from. It will contain rock fragments. Weathering breaks down this parent rock into smaller and smaller pieces of rock This layer is most often light in color.
R bedrock A mass of rock such as granite, basalt, quartzite, limestone, or sandstone that forms the parent material for some soils.
