“A seed cannot grow in stone. It requires fertile soil & water. Compassion is the soil where life grows.”

Amit Ray – Walking the Path of Compassion

What is Soil?

Soil is made up of minerals, dead and live creatures, air, and water, in that order. It is one of our planet’s most dynamic and essential natural resources because these four elements react in amazing ways. Soil, in the eyes of a soil scientist, is the earth’s surface mineral and/or organic layer that has undergone physical, biological, and chemical weathering.

Natural resources such as soils are limited. Because they are constantly forming, they are seen as renewable. Although this is true, they form at a glacial pace. It can take several hundred years or more for one inch of topsoil to decompose.

How it Forms?

Soil is formed continuously, but slowly when rocks break down due to weathering. Physical weathering is the breakdown of rocks because of mechanical activity; chemical weathering is the breakdown of rocks because of chemical action, and biological weathering is the breakdown of rocks because of biological action. Changes in temperature, abrasion, and frost can all cause rocks to break down.

Chemical weathering refers to the deterioration of rocks caused by a change in their chemical composition. When the minerals in rocks react with water, air, or other chemicals, this can happen.

The degradation of rocks by living organisms is known as biological weathering. Plant roots can grow into fractures in the rock, causing it to split. Burrowing animals let water and air get into the rock, and plant roots can grow into crevices in the rock, causing it to break.

Soil formation is further aided by the accumulation of material caused by the action of water, wind, and gravity. These procedures can take tens of thousands of years to complete.

Types of Soil

Different types of soil.
Figure 01: Different soil types.

Soil can be categorized into sand, clay, silt, peat, chalk, and loam types based on the dominating size of the particles within soil.

  • Sandy Soil – Sandy soil is a type of soil that has a high proportion of sand and little clay (clay weighs more than sand) and is warm in spring and dry in summer. The addition of organic matter can help give plants a boost of nutrients by improving the nutrient and water holding capacity.
  • Clay Soil – Clay soils take longer to warm up in summer and dry out and crack in the winter, making them difficult to grow in spring and summer.
  • Silt Soil – Clay soils take longer to warm up in summer and dry out and crack in the winter, making them difficult to grow in spring and summer.
  • Peat Soil – Peat soil – a type of soil that is rich in organic matter and retains a large amount of moisture – is one of the most important nutrients for plants to thrive in.
  • Chalk Soil – Chalky soil is alkaline soil that can’t be acidified and will not support the growth of plants that require more acidic soil for growth. Chalk soil can be either light or heavy but always highly alkaline due to the calcium carbonate (lime) within its structure.
  • Loam Soil – Loam soil is a mixture of sand, silt, and clay that are combined to avoid the negative effects of each type. These soils are fertile, easy to work with and provide good drainage. Depending on their predominant composition they can be either sandy or clay loam.


Soil-grown plants can be utilized for food, clothing, recreation, aesthetics, building materials, and medicine, among other things. Plants require soil for their survival. The construction process relies heavily on the soil. When producing pottery, clay soil is used. Sewage treatment plants make use of soil. Soils can be used to make medicine. There are organisms called microbes that are created in the soil. These microbes are harmful to bacteria; therefore, soils are used to make antibiotics. Skin ointments are also made from soil. Microbes are tiny organisms not visible to the naked eye. Everyday cosmetic products women use is made from soil, examples are foundation, blush, and facial masks.

A sample of soil.
Figure 02: A soil sample.

World Soil Day

Every year on December 5th, World Soil Day (WSD) is commemorated to raise awareness about the importance of healthy soil and to advocate for the long-term management of soil resources. In 2002, the International Union of Soil Sciences (IUSS) proposed a global day to honor soil. FAO has supported the formal foundation of WSD as a global awareness-raising platform under the leadership of the Kingdom of Thailand and within the scope of the Global Soil Partnership.

In June 2013, the FAO Conference unanimously endorsed World Soil Day and recommended that it be officially adopted by the United Nations General Assembly during the 68th session. The United Nations General Assembly responded in December 2013 by establishing the first official World Soil Day on December 5, 2014. The 5th of December was chosen for WSD since it is H.M. King Bhumibol Adulyadej’s formal birthday, and he is the one who officially sanctioned it.

World Soil Day 2021

The campaign “Halt soil salinization, boost soil productivity” for World Soil Day 2021 aims to raise awareness of the importance of maintaining healthy ecosystems and human well-being by addressing the growing challenges in soil management, combating soil salinization, raising soil awareness, and encouraging societies to improve soil health.

World Soil Day 2021 poster.
Figure 03: Poster of the World Soil Day 2021.
Written By:

Sanduni Gunaratne,
1st Year Undergraduate,
Faculty of Science,
University of Colombo.

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