Soil profile: Before we know about the soil profile we need to know about soil. So, the soil is a thin layer of material (consisting of mineral particles, organic material, air, water and decay of dead organism) covers the surface of the earth and connected with the processes of growth of plants and animals directly or indirectly.
Soils are found to contain a series of horizontal layers, the individual layer is called the horizon. All horizons all together form a “soil profile”.
O-horizon: It is the topmost horizon of the soil profile. This horizon is mostly consisting of plants litter, which has accumulated on the soil surface. The color of this horizon is very from brown to black.
A-horizon: This horizon is located beneath the O-horizon in the soil profile. The biological activities, organic matter, nutrients are highest on this horizon. The color of this horizon is dark due to the presence of a large amount of organic matter.
B-horizon: This horizon is located beneath the A-horizon. This horizon holds more moisture. This horizon is generally light in color and less biological activities than the A-horizon.
C-horizon: This horizon is located beneath the B- horizon. It is the lowermost layer of the soil profile. This horizon contains weathered parent rocks.
Uses of soil profile:
The soil profile is an important tool in nutrient management. By examining the soil profile, we can gain information about soil fertility.
Factor affecting the formation of soil:
1) Parent rocks: Soil is formed from parent rock through the process of weathering and erosion. The atmospheric agencies (wind, plants, organism, water, temperature change, condition, and pressure) play an important role in the process of the breakdown of parent rock to form soil.
2) Organism: soil formation is influenced by organisms (such as plants), micro-organisms (such as bacteria or fungi), burrowing insects, animals, and humans. Sometimes the root of plants enters the cracks of rock and grows in it. Due to scarcity of space inside the rock, breakdown the rock into smaller pieces and forms soil. Animals eat plants and their wastes dissolve into the soil slowly.
3) Climate: Temperature affects the rate of weathering. Due to rapid change in temperature from hot to cold, the formation of cracks in the rocks. When rain occurs, rainwater dissolves in the cracks of the rocks and is converted into ice by freezing, which can expand 9% more volume than the water. Ice exerts pressure on both sides of the cracks and breaks down the rock into smaller pieces and forms soil.
4) Time: the formation of soil from the parent rocks takes tens of thousands of years. Soil properties may depend on how long the soil has been weathered.
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