A soil _is a vertical section of the soil from the ground surface to the point where the soil meets the underlying ricks
Answers
Answer:
A soil profile is a vertical section of the soil from the ground surface to the point where the soil meets the underlying ricks.
Explanation:
Answer:
The soil is arranged in layers or horizons during its formation. These layers or horizons are known as the soil profile. It is the vertical section of the soil that is exposed by a soil pit. The layers of soil can easily be identified by the soil colour and size of soil particles. The different layers of soil are:
Topsoil
Subsoil
Parent rock
Each layer of soil has distinct characteristics.
Soil profile helps in determining the role of the soil as well. It helps one to differentiate the given sample of soil from other soil samples based on factors like its colour, texture, structure, and thickness, as well as its chemical composition.
Also refer: Minerals In The Soil And Soil Pollution
Read on to explore what is soil profile and the different layers of soil that make up the soil profile.
Layers of Soil
The soil profile is composed of a series of horizons or layers of soil stacked one on top of the other. These layers or horizons are represented by letters O, A, E, C, B and R.
The O-Horizon
The O horizon is the upper layer of the topsoil which is mainly composed of organic materials such as dried leaves, grasses, dead leaves, small rocks, twigs, surface organisms, fallen trees, and other decomposed organic matter. This horizon of soil is often black brown or dark brown in colour and this is mainly because of the presence of organic content.
The A-Horizon or Topsoil
This layer is rich in organic material and is known as the humus layer. This layer consists of both organic matter and other decomposed materials. The topsoil is soft and porous to hold enough air and water.
In this layer, the seed germination takes place and new roots are produced which grows into a new plant. This layer consists of microorganisms such as earthworms, fungi, bacteria, etc.
The E-Horizon
This layer is composed of nutrients leached from the O and A horizons. This layer is more common in forested areas and has lower clay content.
The B-Horizon or Subsoil
It is the subsurface horizon, present just below the topsoil and above the bedrock. It is comparatively harder and compact than topsoil. It contains less humus, soluble minerals, and organic matter. It is a site of deposition of certain minerals and metal salts such as iron oxide.
This layer holds enough water than the topsoil and is lighter brown due to the presence of clay soil. The soil of horizon-A and horizon-B is often mixed while ploughing the fields.
The C-Horizon or Saprolite
This layer is devoid of any organic matter and is made up of broken bedrock. This layer is also known as saprolite. The geological material present in this zone is cemented.
The R-Horizon
It is a compacted and cemented layer. Different types of rocks such as granite, basalt and limestone are found here.
Explore more about: Preparation of Soil for Agriculture
Apart from the rocks, minerals, and layers, soil profile also consists of a water content, which is referred to as soil moisture.
What Is Soil Moisture?
Water in the soil is referred to as soil moisture. Water absorption in the soil is determined by various factors. It plays a major role in soil formation. As a result of precipitation, water arrives at the surface. The particle size distribution of soil determines its porous nature and causes downward movement of water vertically which is known as infiltration. This penetration continues deep in the layers of soil until it reaches saturation.
Water, on reaching this barrier, cannot seep vertically further, hence moves sideways. Formation of puddles as a result of saturation is called surface ponding which can be long-lasting. Water that is available to plants is called Root zone moisture while surface soil moisture is the water available in the immediate upper region of soil.
Moisture content in the soil can be measured using a device known as Tensiometer. They are water-filled tubes which are sealed with a porous ceramic tip towards the bottom and a gauge at the top which is devoid of air molecules. They are penetrated into the soil till the root level. Water passes between the tip of the device and the ambient soil until it reaches an equilibrium and hence, tension is recorded on the gauge. Readings thus obtained give a measure of soil moisture in that region.
Also Refer: What Is Soil?
Types Of Soil Moisture
The different types of water present in the soil include:
Gravitational Water
The water that reaches the water table of the soil due to the gravitational force is referred to as gravitational water. This is not available to the plants.
Hygroscopic Water
This water is also not available to the plants. It is a thin film of water tightly held by the soil particles.
Explanation:
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