Soil Profile Definition and Types

Kids love playing in parks or gardens, where they find swings, slides, and other games. While playing, they come into contact with soil (an essential part of human life). Do your kids need to know about every crucial thing in their lives? Of course, every parent wants their kids to be aware of most things. Let’s simply explore the soil profile. This article will help you understand different concepts like the soil profile model, moisture content of the soil, layers of soil for kids, etc.

What is the Soil Profile?

Soil is one of the essential natural resources and is vital for agriculture. It protects the plants and supplies water and nutrients. The soil profile definition is “the vertical section of the soil that shows the various layers from the surface to the unaffected parent material is known as a soil profile.” Soil profile consists of various layers, which are known as horizons.

Types of Soil

There are four types of soil.

1) Sand Soil

Sand soils are high in proportions of sand and low in proportions of clay. It is also known as light soil or sandy soil. It is lightweight, warm, dry, and low in nutrients. It is easy to work with this soil because of its quick water drainage.

2) Silt Soil

Silt soil is composed of medium-sized particles. It can be easily compacted and are prone to get eroded with rain due to its fine particles. It is well-drained soil that holds moisture well. It is well-drained soil that retains moisture well.

3) Clay Soil

Clay soil comprises sand, clay, and fine mineral particles. This soil holds a high amount of water due to the spaces between clay particles. It remains wet and cold in winter and dries out in summer.

4) Loam Soil

Loam soil combines sand, silt, and clay soil. It avoids the harmful effects of each type. Loam soil provides good drainage, is fertile, and is easy to work with.

Layers of Soil

There is a total of six layers of soil profile.

1) Horizon – O

The horizon O is an upper layer of topsoil (Horizon-A) known as humus or organic soil. It primarily comprises organic materials such as small rocks, surface organisms, fallen trees, dead leaves, and other decomposed organic materials.

2) Horizon – A

The A horizon is the top layer of the mineral soil horizons, known as “topsoil.” This layer is mainly made up of decayed organic matter called “humus.”

3) Horizon – E

This layer has a lower clay content and is common in forested areas. It combines nutrients leached from two horizons (O and A).

4) Horizon – B

This layer consists of humus, clay, carbonates, etc. It is typically a yellowish-brown to dark brown colour.

5) Horizon – C

This layer lacks the properties of the O, A, E, or B horizons. It is a mineral horizon that excludes cemented and hard bedrock.

6) Horizon – R

This layer is nothing but a compact and solid layer. It includes different types of rocks, such as granite, basalt, and limestone.

What is Soil Moisture?

Soil moisture is a key to controlling the exchange of water and heat energy between the land surface and the atmosphere through evaporation and plant transpiration. Water is essential to absorb nutrients from the soil. It follows the process of transpiration, by which water moves up the stem of a plant from root to leaf. It happens when water is lost from the plant due to evaporation occurring in the leaves.

Types of Soil Moisture

There are three types of Soil Moisture.

1) Gravitational Water

Due to gravity, the amount of water in the soil drains downward is known as gravitational water.

2) Capillary Water

The water that is present in the pores of the soil and gripped against gravity for the roots of the plant to absorb is known as capillary water.

3) Hygroscopic Water

The word “hygroscopic” means a tendency to absorb moisture from the air. So, when the water in the soil forms a fragile, tightly held film around the soil particles, It is known as hygroscopic water.

Importance of Soil Moisture Content

Soil moisture is a critical variable in controlling the exchange of water and heat energy. It happens between the land surface and the atmosphere through evaporation and plant transpiration.

Measuring Soil Moisture

Soil moisture measurement is the most critical part of agriculture. To measure the soil moisture, weigh the wet soil sampled from the field, dry it in an oven, and then weigh the dry soil. Hence, the gravimetric (measurement of weight and gravity) water content equals the wet soil mass, which is subtracted from the dry soil mass and divided by the dry soil mass.

Soil moisture is measured by Tensiometers. This device is a soil moisture measuring instrument and measures soil moisture tension. This works in sealed, water-filled tubes with a porous ceramic tip at the bottom and a vacuum gauge at the top. They are inserted in the soil to the plant’s root zone depth.

Frequently Asked Questions

1) What determines the thickness of the soil profile?

Answer: The thickness of the soil profile is determined by time. One layer of soil takes multiple years to deposit. Many layers of sand, clay, humus, weathered rocks, etc., continue to get deposited over the already present soil layers.

2) What factors decide the moisture content in soil?

Answer: Various factors affect soil moisture, such as terrain, soil characteristics, climate, and vegetation. The effects of these factors change with time and space. Time leads to rainfall patterns, and space leads to soil depth.

3) What is the importance of a soil profile?

Answer: The importance of soil profile directs to healthy plant growth, human nutrition, and water filtration.