Why Is Soil Essential for Life and the Environment?
Our Earth is filled with vast amounts of water bodies as well as enormous trees surrounding us. Do we ever wonder how such big trees stand strong for years and years without any disruption? It is with the help of nothing but the soil. Soil is a part of our mother Earth and it has played a big role in growing plants that provide us with basic resources in our day-to-day life. We cannot ignore the fact that how many trees have been growing and giving us shelter with the help of this soil. But, how does this soil not wear out and keep trees strong? Well, it is because of moisture in the soil.
What is Moisture?
A small amount of wetness is known as moisture. Anything that has little amount of water in it is termed moisture. A small amount of water is nothing but water evaporates before it is collected in a small quantity. Likewise, soil too contains moisture, which helps in the growth of the trees.
Moisture in Soil
Unsaturated water contains a total amount of water along the water vapour. Soil does not come in contact with the water bodies like rivers, lakes, etc. But it has little left in it, enough for the plants that grow in it. Moisture in soil is as important as sunlight to plants because soil moisture helps in transferring required nutrients from the soils to the plants.
Types of Soil Moisture
There are three main types of soil water depending on the interaction of water with soil. They are,
Gravitational Water
The concept of gravity applies to moisture too. Water does not stay in the soil for a long time and is drained away immediately. Only a fraction of water molecules remain here. This happens mainly because of the large pores in the soil.
Capillary Water
In this type, the water molecules are trapped in the soil’s microspores. The water molecules here are more available than the gravitational water. They are not dried out easily, but once the soil is dried up, the water is forced to go down, converting it into gravitational water.
Hygroscopic Water
This is the strongest of the types of soil moisture. This not only stays in the soil pores but is available at the surface of the plants. They don’t dry up easily and keep the plants hydrated for a long time.
How Will You Show that Soil Contains Moisture?
Identifying moisture in the soil is as simple as finding a red ball in a pool of yellow balls. Moisture mainly consists of a small amount of water, which can be identified by heating up the soil. Heating something that has water will cause water to vaporise. Likewise, heating soil in a tube will convert water to water vapour, and the presence of water droplets on the sides of the tube confirms the moisture in the soil.
Using Soil Moisture For Plant Growth
A sufficient amount of moisture in the soil is necessary for the plant to have steady growth. Farmers need to be very careful with this process as an excess amount of water can destroy the roots of the plants. The moisture level in soil needs to be in the range of 20% and 60%. Less amount of soil moisture can lead to wilting of plants. Hence, controlling the range of soil moisture is the right necessity.
Soil Humidity
Humidity is nothing but the hot air surrounding it. Humid air is a problem for plants as it disrupts their routine of transpiring. Humidity also causes root disease, less growth, low quality of plants etc. plants are affected by humidity in both ways, i.e. when it is high or low. If the humidity is high, it affects the soil, drying it to the core. If it is low, it affects the growth of the plants, making it less desirable.
Hence, from this, we understand how humidity can affect the transpiration of life. Humidity is calculated through a hygrometer. It is said that black soil has the most humidity among the other soils, ranging from 150-200 mm/m.
Interesting Facts
About 95% of all food production is supported by soil.
It can take up to 1,000 years to form one centimetre of soil.
A quarter of all known species on earth call soil their home
Clay soil has the highest water-holding capacity among the other soil.
Key Features
Soil moisture controls the exchange of water and heat energy through evaporation and transpiration.
Soil moisture plays an important role in the growth of plants and also helps in agriculture.
There are three types of soils. Gravitational, capillary, and hygroscopic water.
FAQs on What Is Soil? Definition, Types & Key Benefits
1. What is soil and what are its main components?
Soil is the uppermost layer of the Earth's crust, which serves as a natural medium for plant growth. It is a complex mixture of minerals, humus (organic matter), water, air, and countless living organisms. The primary components of soil are weathered rock particles, which provide essential minerals, and organic matter, which enriches the soil with nutrients.
2. What is a soil profile and what are its different layers or horizons?
A soil profile is a vertical cross-section of the soil, from the surface down to the underlying parent rock. It shows distinct layers called horizons. The main horizons are:
O Horizon (Organic): The topmost layer, rich in decomposing organic matter like leaves and twigs.
A Horizon (Topsoil): A dark layer rich in humus and minerals, where most biological activity occurs and plant roots grow.
B Horizon (Subsoil): This layer contains less organic matter but is rich in minerals that have leached down from the topsoil.
C Horizon (Parent Material): Composed of partially weathered rock fragments from which the soil is formed.
R Horizon (Bedrock): The solid, unweathered rock layer that lies beneath all other layers.
3. What are the main types of soil found in India based on texture?
Based on the proportion of different-sized particles, soil is primarily classified into three types: sandy, clayey, and loamy. Sandy soil has large particles and does not hold water well. Clayey soil has very fine particles and holds a lot of water but has poor aeration. Loamy soil is a balanced mixture of sand, silt, and clay, making it the most suitable for agriculture.
4. Why is soil considered a vital natural resource for life on Earth?
Soil is vital for several reasons. It is the foundation for agriculture, providing anchorage and essential nutrients for plants that feed humans and animals. It acts as a natural water filter, purifying groundwater. Furthermore, soil serves as a habitat for a vast range of organisms like bacteria, fungi, and insects, which are crucial for nutrient cycling and decomposition.
5. How do sandy and clayey soils differ in their properties?
Sandy and clayey soils differ significantly due to their particle size. Sandy soil consists of large, coarse particles, leading to large pore spaces, excellent aeration, and rapid water drainage, but poor water and nutrient retention. In contrast, clayey soil is made of very fine particles, resulting in small pore spaces, high water-holding capacity, and good nutrient retention, but it is heavy and poorly aerated when wet.
6. What is meant by the percolation rate of soil?
The percolation rate refers to the speed at which water moves downward through the soil. It is a measure of the soil's drainage capacity. This rate is highest in sandy soil because of its large particles and pores, and lowest in clayey soil, where the fine, densely packed particles slow down water movement significantly.
7. What are the primary causes of soil erosion and how does it impact the environment?
Soil erosion is the removal of the fertile topsoil by natural forces like wind and water. The primary causes are human activities such as deforestation, overgrazing, and improper farming techniques, which leave the soil bare and vulnerable. The major environmental impact is the loss of soil fertility, which reduces agricultural productivity, clogs rivers with sediment, and can lead to desertification.
8. What is humus and why is it important for soil fertility?
Humus is the dark, organic substance in soil that forms from the decomposition of plant and animal matter by microorganisms. It is critically important for soil fertility because it is rich in nutrients essential for plant growth, improves the soil's structure for better root penetration, and significantly increases the soil's water-holding capacity, helping plants survive dry periods.
9. Why is loamy soil often considered the best type for growing most crops?
Loamy soil is considered ideal for most crops because it combines the beneficial properties of sand, silt, and clay. It has enough large particles (sand) to ensure good drainage and aeration, and enough fine particles (clay and silt) to provide excellent water and nutrient retention. This balanced composition creates a perfect environment for plant roots to grow and absorb what they need.
