Properties of Soil

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What is Soil?

It is a mixture of minerals, organic matter, liquids, gases, small organisms that altogether support life. It is the upper layer of the earth’s surface composed of a mixture of organic remains, clay, and rock materials on which plants grow. It supports plant life and growth. It continually undergoes development by numerous physical, chemical, and biological processes, which include weathering and erosion. The density of soil is 1.6 g/cm3.


Physical Properties of Soil

Physical properties of soil include colour, texture, structure, porosity, density, temperature, and air. The colors of soil vary widely from place to place and indicate some properties like organic matter, water, and redox conditions of the soil. Soil texture, structure, porosity, density, are related to the types of soil particles and their arrangement.

Soil Texture: Soil texture definition (such as loam, sandy loam, or clay) refers to the proportion of sand, silt, and clay-sized particles that make up the mineral fraction of the soil. Sand and silt are of no importance to the soil as they don’t contribute to the soil’s ability to restore water and nutrients. Clay is an active part of soil texture as it has a small size and has a large amount of surface area per unit mass and it helps in storing water and ions. The texture of soil helps to know about the amount of water that soil can hold, the rate of water movement through the soil, how workable and fertile the soil is.

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Absorption of Water:  Soil is able to absorb water because of its porosity. Water holding capacity is different for different types of soils. Sand absorbs less water than clay. Sandy soil water holding capacity is less than clay soil and loamy soil. Clay soil holds more water than sandy soil.

Soil Colour: Soils are of different colors (brown, yellow, red) depends on oxidized or ferric iron compounds. The darker the color of the soil, the more organic content it contains. The red color of the soil is due to the presence of iron oxide and The black color soil is rich in minerals and humus. 

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Soil Horizon: The soil is divided into different horizons from top to bottom:

A-Horizon: The uppermost layer of soil is called topsoil. This layer mostly contains minerals from parent material with organic matter. A good material for plants and other organisms to live is found on this horizon.

B-Horizon: This is the second layer from the top and is a little rich in humus and it supports moisture. This layer consists of clay, silt, nutrients, and weathered rocks. Minerals present in this layer are more in comparison to the top layer.

C-Horizon: This is the third most layer from the top, and it consists of small pieces of rocks broken down due to weathering.

BedRock: This is the last layer of the soil and consists of layers of solid unweathered rock.

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The pH of Soil: Soil can be acidic, alkaline, or neutral. Some plants grow well in acidic soil such as potatoes. Plants like the bean, garlic grows well in the basic type of soil, Carrots and lettuces prefer neutral soil. The pH of soil under the chemical properties of soil, Other chemical properties include Calcium carbonate content, Soil sodicity, Soil nitrogen, etc. 


Soil Structure Definition

Soil structure can be defined as the way individual particles of sand, silt, and clay are assembled together. Single particles when assembled appear as larger particles. These are called aggregates. Humus is a major deciding factor to know about the structure of soil because it causes the soil to become more porous and allows water and air to penetrate deep underground. 


Types of Soil Structure

  • Very fine or very thin

  • Fine or thin

  • Medium

  • Coarse or thick

  • Very coarse or very thick.


Soil Conservation 

Soil conservation is the process of prevention of loss of the topmost layer of the soil from erosion or prevention of reduced fertility caused by over usage, acidification, salinization, or other chemical soil contamination.  By conserving soil we can preserve the fertility of the soil. Few methods to conserve them are:

  • Terrace farming

  • Soil-conservation farming

  • Use of Green Manures

  • Salinity management, etc

FAQ (Frequently Asked Questions)

1. Explain the properties of soil

The properties of soil comprises its physical properties, strength parameters, permeability characteristics, index properties, consolidation properties, modulus parameters, dynamic behavior, etc.

2. Explain the percolation property of soil

The process in which water passes down slowly through the soil is termed percolation of water.  

When we sprinkle a small amount of water on the ground, it is soon absorbed by the soil, this is because water percolates through the soil. The rate of percolation of soil is different in all types of soils.

3. What are the different types of soil?

Soil is classified into four types:

  • Sandy soil.

  • Silt Soil.

  • Clay Soil.

  • Loamy Soil.

Sandy Soil: This is one of the poorest types of soil for growing plants because it has very low nutrients and poor water holding capacity, It is very good for the drainage system.


Slit Soil: It is the smooth and fine quality of the soil that holds water better than sand. It is a light and moisture-retentive soil type with a high fertility rating. As the particles of this soil are fine, they can be easily compressed and are prone to washing away with rain very easily.


Clay Soil: This soil has very good water storage qualities and makes it hard for moisture and air to penetrate into it. It is very sticky to the touch, it remains wet and cold in winter and dries out in summer.


Loamy Soil:  it has the ability to retain moisture and nutrients So, it is more suitable for farming. This soil is also referred to as agricultural soil as it includes an equilibrium of all three types of soil materials being sandy, clay, silt, and humus.