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What is Subsoil?

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Soil is the top and thin layer present on the surface of the Earth and it consists of various types such as silt, sand, clay, peat, loam, chalk, and various other types. We generally study the soil profile before jumping into various types of soil. The soil profile is nothing but a vertical representation of the various layers of the soil where every layer has different characteristics such as texture, colour, depth, composition, benefits, etc. Here, in this article, we will be discussing one of these layers comprehensively and will come to know what role this particular layer plays in the soil profile. 

In this, we will learn about subsoil, subsoil definition, subsoil meaning, its various types, characteristics, merits and other related aspects. This topic will help you in Geography and Geology or Geomorphology.


Introduction

Soil is formed by the actions of water, wind or climate and breaking down of rocks, etc. and it is the thin as well as the topmost layer of the crust of the Earth which consists of rock particles as well as organic matter. Its formation is basically based on the parent rock, climate, surface relief and natural vegetation. It is the platform where plant kingdom establish themselves and it is one of the most important and recognised functions of the soil is that it supports food production and plant growth by providing food and water to them. The study of this is known as pedology and V.V. Dokuchaev who was a Russian and was considered as the one who laid down the foundation of modern pedology.

There are different layers of soil under the crust of the Earth and also different types of soil are also found on the Earth. The layers of the soil can be divided into different horizons such as O Horizon, A Horizon, E Horizon, B Horizon, C Horizon and R Horizon. In this article, we are discussing the B Horizon or we can say the subsoil.


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Subsoil Meaning

As per the soil profile, this is a kind of soil that lies below the surface soil but above the bedrocks. It is also called undersoil and B Horizon soil. It lies between E Horizon and C Horizon. It predominantly consists of leached materials as well as minerals also such as iron and aluminium compounds. The microscopic and macroscopic organisms help in making the surface soil rich but these organisms spend very little time in this subsoil soil. Below this layer, there is a layer of partially disintegrated rocks and below is a hard rock found. If we talk about the layers of other soil and subsoil, a Horizon is a topsoil layer, E Horizon is a leaching layer and subsoil is a layer present below them and contains minerals and organic matter from both above layers. Thus, mostly it contains a mixture and variables of the particles similar to the surface soil but it contains less humus or less percentage of organic matter.


Subsoil Definition 

Some of the standard definitions are given below:

  • "Subsoil is the stratum of weathered material that underlies the surface soil" - Merriam-Webster

  • "The subsoil is a layer of earth that is just below the surface soil but above the hard rock." Or "the bed or stratum of earth or earthy material immediately under the surface soil." - Collins dictionary


Features

The various characteristics of subsoil are mentioned below:

  • It does not contain many plant nutrients but contains more minerals than the surface layer such as iron and aluminium compounds.

  • It is sticky and light in colour.

  • It is less fertile.

  • It is also very challenging to manage this kind of soil.

  • Water passes through the above soil to it and thus affects it as well.

  • If we talk about subsoil compaction, It is more compact than the surface soil as it does not contain any air, and thus microorganisms and macroeconomics do not live here for long and no insects can survive here.

  • It is also called undersoil.

  • Clay, as well as human remains, are also accumulated here in this layer.


Benefits

Subsoil provides a number of benefits which are mentioned below:

  • It helps and plays a vital role in the absorption of the water as well as drainage.

  • It also supports hard features of the landscape like fencing, patios and paths, etc. Thus, it helps in giving strength to the plants whenever it rains.

  • It is also rich in minerals and also helps in the growth of plants.


Types of Subsoil

It has a mixture of variable and small particles similar to the surface soil ie. sand, silt and clay but it has less percentage of humus as well as organic matter. The major types of this are mentioned below:


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  • Sandy: It is one of the foremost types of this layer which consists of small particles of disintegrated and weathered rocks particles. It is considered the poorest type of soil for growing plants. It is less fertile and has fewer nutrients as well as poor water holding capacity. Thus, it becomes very hard for the roots of the plants to hold water here but it is good for the drainage system. 

  • Clay: This type of soil contains the most finely grained particles with the presence of clay minerals and it contains the smallest particles as compared to other sandy and silt types of soil. Here, these particles are tightly packed where there is no airspace. It has good water holding capacity which makes it hard for air and moisture to penetrate. When it is wet, it becomes very sticky but it becomes smooth when it is dried. It does not drain well and it is also considered the heaviest and the densest type of soil.

  • Gravel: It is a type of granular soil that consists of coarse particles like sand and gravel. It is also called crushed stones. It is a combination and aggregation of fragmented rocks. It consists of loosely attached particles and it is not good for plant growth.

  • Hard Rock: Usually, the soil is made up of breaking down rocks and it has different layers and at some point, hard rock soil can be seen as well which are formed by a number of various rocks that contain various minerals. This type of soil provides a good and strong foundation. This is the soil that helps in giving strength to the above soil and plants present on it and other landscape features whenever it rains or storms occur.


Did You Know?

  • The word soil is known with different words in different regions or languages such as in Malay or Indonesian, it is known as Tanah and thus Tanah subsoil is also known in this way whereas in Danish soil is called as Jord or in Dutch as Grond.


Conclusion

Therefore, we can say at the end that subsoil acts as a base for the above soil and also provides strength to the surface soil. Though it does not contain so many nutrients which help in plant growth and it is not a fertile layer as compared to topsoil but it has its importance and contains the same variables as the surface soil such as sand, clay, silt etc. This subsoil lies below Horizon A and E and thus contains all the material passed by the above two layers. It helps in gardening activities and providing strength to the plants. In this article, we have covered the subsoil meaning along with various standard subsoil definition, types of subsoil, its features and benefits, etc. This article will help you whenever you study the soil profile and layers of the soil in Geography or Geology.

FAQ (Frequently Asked Questions)

1. What is Soil?

Answer. The layer present on the surface of the crust that supports life is called soil. It consists of various minerals, organic matter, nutrients, air, water, gases, etc. and is a thin layer present on the crust of the Earth. Food production and plant growth is a vital function of soil along with providing a home to various micro and macro-organisms. According to the soil profile, it can be divided into various soil layers which have different properties and importance.

2. What is Subsoil? Give its Definition.

Answer. It is the undersoil that lies below the surface soil. According to the soil profile, it lies below the O Horizon, A Horizon and E Horizon but above the C Horizon and R Horizon. It is a B Horizon soil that lies in between these layers and it is not fertile because it does not contain those nutrients that help in the growth of the plants. It contains a lot of minerals such as iron and aluminium and has less percentage of humus and organic matter. According to the Collins dictionary, "The subsoil is a layer of earth that is just below the surface soil but above hard rock."

3. What are the Characteristics or Merits of Subsoil?

Answer. It has various characteristics and uses. It does not contain many plant nutrients but contains more minerals than the surface layer and is sticky and light in colour and also less fertile. On the other hand, It is also very challenging to manage this kind of soil. Water passes through the layers affects it as well and It is more compact than the surface soil whereas clay, as well as human remains, are also accumulated here in this layer. It helps in absorption of the water as well as drainage and also supports hard features of the landscape and helps in giving strength to the plants whenever it rains whereas It is also rich in minerals which also helps in the growth of the plants.