What Is Soil (original) (raw)

Last Updated : 23 Jul, 2025

**Soil is the loose material that covers the Earth's surface in most parts of the world. It gives plants the nutrients they need to grow and plants give people and animals food to live. Soil also provides building materials, homes for animals, and things we use every day. More than just dirt, soil is a valuable natural resource that serves as the basis for life as we know it on Earth. Rocks, decaying plants and animals, air, and water all makeup soil. By the process of weathering big rocks break down into smaller and smaller pieces eventually, becoming part of soil.

Table of Content

• What is Soil?
• Composition of Soil
• Formation of Soil
• Factors Influencing Soil Formation
• Characteristics of Soil
• Types of Soil
• Importance of Soil

What is Soil?

Soil is the **top layer of the earth's crust composed of mineral particles, organic matter, water, and air. It's a living, dynamic **ecosystem that supports plant life and plays a vital role in the environment. Soil is formed when rocks break down into tiny pieces due to repeated drying, heating, and cooing by sun, wind, and rain, This process is called **weathering.

Water seeps through the fractures in the rocks during the rainy season. This water freezes in the cold and creates pressure, which causes rocks to shatter. This reduces the already tiny rock fragments into even **smaller fragments known as pebbles. Eventually, the stones crumble into small soil particles. When the soil is contaminated with humus (dead and decayed small animals and plants) it is good for the growth of the plants. There are three main layers of soil- **topsoil, subsoil, and bedrock. The topsoil layer is best for plant growth while the subsoil has very little humus and is orange. Bedrock is quite deep inside the earth.

Composition of Soil

The composition of soil is mentioned below:

• Soil is composed of 3 things: **Inorganic components (minerals), organic components, water, and air.
• In reality, the percentage of the four components varies tremendously, but on a broad basis the composition is 45% minerals, 20-30% air, and 5% organic matter.
• Water and air are present in spaces between the soil particles but there is variation in the ratio of pores filled by air and water.
• The ratio may vary seasonally, weekly, or even daily.

Inorganic Components of Soil

They are derived from rocks and minerals. 50% of the total mass of the soil is inorganic minerals. The inorganic components are important as:

• They are responsible for soil mass and volume.
• They provide nutrients important for plant growth.
• They supply materials for the formation of other minerals also.

Organic Components of Soil

The percentage of organic matter in the soil is <5%.

• It largely determines soil productivity, as provides food for **microorganisms, and other nutrients to the plants and supplies more oxygen to the plant roots.
• The physical properties of soil are also altered by chemical reactions such as ion exchange.
• The decomposition of plants nutrient and animal matter results in the building of organics into the soil.
• It is an important component of soil as it holds soil particles together and stabilizes them and reduce the risk of erosion, improves the ability of soil to transfer air and water.
• Major organic compounds in the soil are fats, waxes, saccharides, and nitrogen.

Water and Air in the soil

Mineral soil consists of 20-30% of water and only half of it is available to plants.

• It acts as a medium for the transport of essential plant nutrients from soil to roots and to the farthest reaches of the plant leaf structure.
• Soil water is part of the global hydrological cycle, which shows how water that falls as precipitation returns to the **atmosphere through **transpiration and evaporation.

Formation of Soil

Soil formation is the most complicated and slow process. It will take several years that is 100 to 1,000 years the conversion of parent material into soil known as soil formation. This process was carried out by the following factors:

Factors Influencing Soil Formation

Various factors influence soil formation like:

• Climate, temperature, and **precipitation affect weathering and decomposition rates.
• Organisms, microorganisms, plants, and animals contribute to soil formation through decomposition and nutrient cycling.
• Topography, slope, and landscape influence soil erosion and deposition.
• Parent material is the initial geological material from which soil forms.
• Time, the duration of soil development.

Characteristics of Soil

Some of the important characteristics of soil are mentioned below:

• Soil forms at the surface of land.
• Soil is the skin of the earth.
• Life on Earth depends on soil as soil supports plant life.
• Soil is a complex mixture of rocks, minerals, water, air, organic matter and countless organisms that are decaying remains on once living things.
• Soil is a system in which energy and matter from the sun, the atmosphere, and living organisms penetrate and interact.
• The gaps between aggregates or soil particles are known as pores. They are crucial because they permit both the movement of air and water through and the storage of water in the soil.
• The origin of the soil, the length of time it has been forming, and the surrounding conditions all affect the colour of the soil.
• The depth of the soil controls how much water and how far roots can spread. The lowest root-limiting layer is used to measure depth.
• Soil drainage is a way of expressing the frequency and duration of periods in which the soil is saturated. Excess free water in the root zone can kill plants or keep them from becoming established.

Types of Soil

Soil can be categorized into three primary types based on particle size.

• **Sandy soil: This soil has coarse particles, and good drainage, but low fertility.
• **Silt soil: It has fine particles, good fertility, and drainage.
• **Clay soil: It has very fine particles, and excellent fertility, but poor drainage.
• **Loamy Soil: Loamy soil is a mixture of clay, sand, and silt that contains extra organic matter and is extremely productive.

Importance of Soil

Soil is important because of the following reasons:

• Healthy soil is a foundation for our food system.
• For farmers, soil temperature is important, particularly for spring planting. A minimum temperature is required for the germination of many seeds.
• Soil purifies the water that we drink.
• Soil critical in its role in the regulation of **greenhouse gases, because it's our major store of carbon.
• Soil is the mixture of minerals, organic materials, moisture, and air that makes a home for billions of animals, plants, and fungal species.
• Different varieties of soil are useful for specific purpose like for agriculture, gardening, construction, and environmental conservation.

**Also Read:

• Soil Pollution
• Soil Profile
• Types of Soil
• Soil Conservation Method
• What are the factors responsible for the formation of Soil?