Did you notice the sand the last time you went to the beach? And the ground on your last visit to the football field? The soil in both these places is distinctively different. Have you ever wondered why soil is a different texture and colour at different places? This is due to the different minerals in soil. Let us learn more about this.
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Soil Formation
Soil is the thin layer of loose material covering the earth’s surface. It is composed of both organic and inorganic materials. The formation of soil is an extremely long process taking up to an average of a thousand years. Soil is formed when surface rocks break into several smaller particles, called regolith, which then gets mixed with varied organic matter. This whole process is called Weathering. So weathering happens through three major ways, namely
- Physical Weathering: This is the geological process when rocks get fragmented into smaller particles, without changing the chemical composition of the rocks. This primarily happens due to fluctuating temperatures causing the rocks to break apart.
- Chemical Weathering: This is the erosion of rocks and other surface materials caused due to chemical reactions. The rocks react with substances in the atmosphere, such as moisture, air, water etc. The resulting substance has a different chemical composition than the rock from which it formed. Hydration, Hydrolysis, Oxidation, Carbonation and Reduction are the chemical processes involved in chemical weathering.
- Biological Weathering: This is the process of disintegration of rocks due to actions of living organisms (animals, plants, microbes etc), like when a plant grows in the fissure of a rock and its roots exert pressure on the rock forcing in to break apart. Even microbes produce organic material that causes weathering.
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Soil Composition
Soil is essential a mix of various particles and substances. So let us have a look at all the things that make up soil,
- Minerals: A very important substance found in soil. Minerals basically formed by the break down of large rocks. Some of the most common minerals found in soil are, Iron, Potassium, Magnesium, Calcium, Sulphur etc.
- Humus: Humus is the organic substances that are formed due to decomposition of dead and decomposing plants and animals. It lends the soil its fertility.
- Living Organisms: These are mostly microbes and other organisms (such as worms, bacteria, fungi etc.) that live in the soil and perform the decomposition of animals and plants that gives the soil humus.
- Water and Air: Water and air form a part of the soil and allow living organisms to perform their functions. They also help in the process of photosynthesis.
Minerals in Soil
As we have seen above, soil is a mixture of various components. Now let us explore the importance of the minerals present in the soil. Minerals are the largest component in the soil, making up almost 40% to 45% of the total components. The minerals in the soil are classified into two categories, namely
- Primary Minerals in soil: These are minerals which have not been chemically altered since deposition. They are same or similar to their parent materials. Often these materials are bigger in size and irregular in shape. These primary minerals are usually found in sand and silt.
- Secondary Minerals in soil: These are minerals formed as a result of weathering of Primary Minerals. Secondary minerals are mainly found in fine silt or clay. The particle size of these minerals is much smaller, due to the weathering process. These minerals have a large surface area that helps them retain moisture.
Now one of the most important functions of minerals in soil is the assistance it provides to plant life. Plants need a number of minerals for a healthy life and growth. These minerals are absorbed from the soil via the roots of the plants and trees. The two most important a plant needs are nitrate and magnesium. Nitrate is the main source of amino acids which are the main ingredient required to make proteins. Magnesium is essential in the production of chlorophyll which allows photosynthesis. If these essential minerals are not available to plants, its stunts their growth.
Soil Pollution: Causes and Prevention
When soil and its profile is altered by either removal of essential materials or addition of pollutants, which results in the reduction of the productivity or fertility of soil, it is called Soil Pollution.
Soil is degraded due to various factors, some of which are
- Manmade efforts
- Agricultural Waste
- Industrial Waste
- Acid rain
- Radioactive Waste
Prevention of Soil Pollution
There are many steps that can be taken to control unchecked soil pollution, to ensure the fertility of soil remains at ideal levels. Let us discuss a few measures that can be put into effect
1) Soil erosion can be reduced by many agricultural and farm activities. There are many practices that can be followed to reduce erosion, such as
- To avoid the topsoil being washed away we should plant more trees
- Reduce deforestation and commercial exploitation of forests
- Replace chemical fertilizers in farming with natural manure
2) Proper disposal of waste material. Instead of dumping waste material without treating it, we should take up the practice of separation and treatment of waste materials, ensuring that they do not harm the environment,
3) A great alternative to the standard commercial chemical fertilizers is biofertilizers. As opposed to chemical fertilizers they do not leach harmful acidic chemicals into the soil.
4) Reuse, Recycle & Reduce: This is regarding non-biodegradable materials, such as plastics, metals, glass etc. If we follow the reuse, recycle and reduce policy it will have a huge impact on our waste production and a very positive impact on the environment, reducing various kinds of pollution including soil pollution.
Hopefully, this lesson has helped you understand the significance of soil in our atmosphere, and the importance of minerals in the soil. By following these practices let us ensure that these minerals stay in the soil, and we greatly reduce the erosion and pollution of soil.
Solved Example for You
Q: The holding capacity is highest in
- Clay soil
- Loam soil
- Silt soil
- Sandy soil
Solution: The correct answer is “a”. Clay has the smallest size soil particles, which discourages water percolation, and instead holds the moisture. Clay also has very less aeration, because water displaces air between the spaces of clay particles.
