what are layers of the soil explain
Answers
Answer:
The soil is divided into various different layers top to bottom and this arrangement is termed as the soil horizons. The categorization into various soil layers is known as the soil profile. The soil horizons ranges from the fertile, organic upper layers composed of the top soil and humus to the underlying rock layers composed of the subsoil, regolith and the bedrock. Each layer is of different make up, texture, age and characteristic.
Explanation:
The O-Horizon:
The O-Horizon is the superficial or topmost layer of the soil that is primarily composed of decaying organic matter, living organism, and fresh soil. The color of the topmost layer is normally either brown or black due to its organic composition. It is the layer that hosts most of the roots of small vegetation cover like grass and contains about 20% of organic matter.
The A-Horizon:
The A-Horizon is the second layer of the soil. It is referred to as the top-soil. It is composed of highly decaying organic matter and minerals, and its color ranges from gray to brown. It is the layer that hosts many plants and supports many agricultural and grassland areas. Thus, seed germination and the growth of plant roots take place in this soil layer. It is distinguishable by the different soil types including loam, clay, sand, and silt. It is also the soil layer that is most vulnerable to water and wind erosion.
The E-Horizon:
This is the third and the thinnest soil layer, and it is lighter in color compared to the A-Horizon. It is termed as the eluviation layer due to the leaching of minerals. As a result, this layer is depleted of aluminum, clay, organic compounds, and other soluble elements. It is mainly made up of silt and sand after losing most of its minerals as they drip down through the soil.
The B-Horizon:
The B-horizon is the fourth layer and is also referred to as the sub-soil. It is mainly made up of large rocks, clay, and bedrock. The color of the sub-soil is lighter than the layers above it and ranges from rust to tan. It is also composed of minerals and little organic matter. The sub-soil accumulates a lot of clay, aluminum, iron, and organic compounds from the layers above it from the dripping down of mineralized water through a process known as illuviation. Hence, it is sometimes called the illuviation zone. It is the layer where the roots of big trees end.
The C-Horizon:
This is the fifth layer of the soil and it also known as the regolith. Plant roots do not go through this layer and it has very little organic matter. The color of the C-Horizon is gray and is made up of fragmented pieces of bedrock. Also, it has compacted sediment and cemented geological material. Very little activity is present in this layer but there may be instance of additions or losses of minerals and other soluble compounds.
The R-Horizon:
The R-Horizon is the sixth and final layer of the soil. It is also known as the bedrock. The materials here are mainly solid unweathered rock that are cemented and compacted by the weight of the overlying layers. The color of this layer is gray with several hard rocks. This layer is beyond 50 meters from the top-soil. Some of the rocks found here include granite, limestone, and basalt.