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What is Soil? A Detailed Summary

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What is Soil Moisture?

IVSAT 2024

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.

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FAQs on What is Soil? A Detailed Summary

1. What causes moisture in soil?

Soil moisture is in the water stored in the soil and is affected by precipitation, temperature, soil characteristics, and more. These same factors help determine the type of biome present and land suitability for growing crops. The health of the crops relies on an adequate supply of moisture and soil nutrients, among other things. As moisture availability declines, the normal function and growth of plants are disrupted. As climate changes, moisture availability is becoming more variable.

2. What is normal soil moisture?

It is important to note that most plants and flowers require moisture levels between 21% - 40%. While all the vegetables require about 41% - 80%. There are several tips which can help maintain good soil for moisture. Adding compost or organic matter can help in sandy and heavy clay soils. One inch of water is required for most of the plants. For quick moisture, placing a towel or tissue can indicate the wetness of the soil. 

3. Why should potted plants stay wet?

Soil plays a crucial role in the survival of both outdoor and indoor plants. A houseplant requires air, water, and potting soil for proper growth and development. Soil provides your indoor plants with a base for their roots and essential nutrients for them to grow. It also filters and regulates the discharge of excess water. Soil stores organic carbon and protects against indoor pollutants.

5. What are soil horizons?

Every soil is made up of layers, which we call horizons. The horizons form a soil’s profile. Most soils have the three main horizons, i.e. A, B, and C, and some also have an organic horizon, O. Here are the different horizons that make up the soil:

  • O (Humus or Organic): It is mostly organic matter like decomposing leaves. This horizon could be thick, thin, or absent.

  • A (Topsoil): This is made up of minerals from parent material, plus organic matter. A good place for plants and other organisms to sustain themselves.

  • E (Eluviated): This layer is leached of minerals, clay, and organic matter, and is made up of sand and silt particles of resistant materials like quartz. This horizon is often found in older soils and forest soils, and is missing in some.

  • B (Subsoil): This part is rich in minerals that have been leached from the A or E horizons.

  • C (Parent Material): It is made up of the same parent material that the soil has developed from, and is found at the surface of the earth.

  • R (Bedrock): It is a mass of rock such as quartzite, limestone, sandstone or granite, among others, that form the parent material for soils. This is if the bedrock has enough proximity to the surface to allow the weathering.