Soil Pollution: Definition, Causes & Effects

Soil Pollution: Pollution affects more than just the air we breathe or the water we drink. When we talk about pollution, what comes to mind first is air pollution and water pollution, but soil pollution is an equally concerning phenomenon that affects the fruits and vegetables we consume every day and deteriorates groundwater quality as well. The pollution in the soil gets to us directly, as we consume these fruits and vegetables.

The main reason the soil becomes contaminated is due to man-made and natural waste triggered by various activities such as sprinkling pesticides in the soil, plastics, biological waste and toxins, industrial waste, acid rains, etc. In this article, we will learn more about the causes of soil pollution and how to prevent it.

What is Soil Pollution?

Soil is the unconsolidated mineral or organic material on the immediate surface of the earth. It is the natural medium for the growth of plants-our primary producers. The uppermost topsoil is the organic portion, which is derived from the decayed remains of plants and animals that adds up to the fertility of the soil. Below the topsoil lies the inorganic portion made up of rock fragments formed over thousands of years by the physical and chemical weathering of bedrock.

The ground below our feet is much more than rocks, soil and silt. Every square metre can be unique in terms of its composition, its structure and the life that it contains and supports. This unique structure of the earth, when altered or contaminated by natural or man-made pollutants, results in soil pollution.

As indicated by the Food and Agricultural Organization of the United Nations (FAO), Soil pollution is a global threat that is particularly serious in regions like Europe, Eurasia, Asia and North Africa. One-third of the world’s soil is currently under threat.

Sources of Soil Pollution

A large number of wastes and new types of pollutants are produced by various types of activities, including agriculture, industry and transportation. Soil, air and water have traditionally been used as sites for the disposal of all these wastes. Based on the nature of pollutants added to the soil structure, sources of soil pollution are as follows:

(a) Through Natural Pollutants

1. Plant Residue – Organic matter is added to the soil to increase the quality of the soil whereas, there lies an underlying fact that the dead remains of plants carry pathogens and pests which degrade the soil.

2. Animal Waste – Soil gets a large amount of human, animal and bird excreta which constitute a major source of land pollution by biological agents.

(b) Through Man-made Pollutants

1. Industrial waste: Industrial waste mostly comprises solid and liquid waste. The liquid discharge from industries is, however, dumped into water bodies, the solid waste is easily dumped onto the soil. These wastes are loaded with poisonous compounds and heavy metals, which ultimately enter the food chain. The main waste product from the mining and smelting industry is mud and rubble, which contain a high concentration of mercury.

These wastes are disposed of directly in the river, which is also used as a source of irrigation water or for domestic activities. Plant products obtained from irrigating with this wastewater is highly contaminated with mercury. Fly ash from thermal power plants, effluents from the dyes and paints industry, along petroleum hydrocarbons all add up to the contamination of soil.

2. Use of detergents: The laundry wastewater is highly polluted with bleaching agents. These chemicals hamper soil health by increasing the alkalinity of the soil. These are poor biodegradable substances that subsequently deteriorates plant growth and production.

3. Agricultural practices: The main agricultural source of Soil pollution is caused by the overuse of fertilisers and pesticides. Agricultural wastes include a wide range of organic materials, often containing pesticides, animal wastes, and timber by-products. The use of phosphate fertilisers induces lead and cadmium content in the soil. All these practices result in decreasing the pH level of the soil.

4. Solid waste: Many of the urban citizens in the developing world have no access to proper disposal of municipal waste and sewerage systems which is resulting in severe pollution of their surroundings. One of the most important urban waste is municipal garbage. This is made up of materials discarded by homes and industry. It contains paper, plastic, and organic materials. Some of these can be recycled by composting, or they may be burnt or disposed of in landfills.

These landfills mostly contain biomedical wastes, which are generally non-degradable. Plastics, one of the major soil polluters, is itself a major problem, from filling up landfill sites, clogging rivers to generating pollution through open burning or incineration.

Half of all plastic produced is designed to be used only once — and then thrown away. Today we produce around \(300\) million tonnes of plastic every year. That is nearly equal to the entire human population.

5. Acid rain: Acid rain is the aftereffect of air pollution. It is caused when pollutants present in the air mixes up with the rain and fall back on the ground. This acidic water could dissolve away some of the important nutrients found in soil and change the structure of the soil. The number of microorganisms present in the soil also decreases as the soil becomes more acidic.

6. Seepage from landfills: Biomedical wastes, solid waste contaminated with radioactive elements, are often dumped into landfills. The seepage from these landfills degrades the soil quality. Plants take up these elements, thereby polluting the entire food chain.

Causes of Soil Pollution

Soil pollution is a complex phenomenon. From the littering of cigarette butts to excess use of chemical fertilisers all lead up to deterioration of soil’s health. Among the most common causes of soil contamination caused by human activity, the FAO highlights industry, mining, military activities, waste — which includes technological waste — and wastewater management, farming, stock breeding, the building of urban and transport as the primary causes of soil pollution. However, some of the leading causes are listed below.

1. Industrial Activity

In the last century, industrial activity has been the biggest contributor to the problem of soil pollution. It has led to an increase in the amount of mining and manufacturing. Most industries are dependent on extracting minerals from the earth. In the course of doing so, the product they obtain is accompanied by a huge amount of waste. This waste is dumped into the surface of the earth.

Whether it is iron ore or coal, the by-products are contaminated, and they are not disposed of in a manner that could be considered safe. As a result, the industrial waste lingers on the soil surface for a long time and makes it unsuitable for use.

2. Agricultural Activities

The utilisation of chemicals in the agricultural sector has gone up tremendously since technological advancement provided us with modern pesticides and fertilisers. These pesticides and fertilisers are full of chemicals that are not produced in nature and cannot be broken down by decomposers. As a result, they seep into the ground, mix with water and slowly reduce the fertility of the soil.

Few other chemicals damage the composition of the soil and make it easier to be eroded by water and air. As plants are primary producers of food, absorption of these chemicals greatly affects the food chain. The decomposition of these plants causes soil pollution as they become a part of the soil.

3. Waste Disposal

In today’s modern times, there is a growing concern over proper waste disposal. Besides industrial waste, human waste also causes contamination of the soil.  Every human adds up to soil pollution by releasing personal waste products in the form of urine and faeces.

While much of it moves into the sewer system, there is also a large amount that is dumped directly into landfills in the form of diapers. Even the sewer system ends at the landfill, where the biological waste pollutes the soil and water. As our bodies are full of toxins and chemicals, when human wastes are disposed into landfills, it causes soil pollution.

Plastic waste greatly contributes to making the soil ill. Though it has numerous uses, its thrown way culture has become a major headache for the entire world. Plastic bags and food wrappers have a lifespan of mere minutes to hours, yet they may persist in the environment for hundreds of years.

4. Accidental Oil Spills

Oil spillage greatly affects the soil’s physical properties. Soil porosity is essential To maintain proper health for cultivation. When spillages happen accidentally, the oil forms a layer on the soil and clogs its pores. This reduces soil aeration and infiltration of water into the soil. Microorganisms responsible for maintaining the soil quality largely suffer. Oils increase the soil’s pH, thereby decreasing crop production.

5. Acid Rain

Soil is the only wealth upon which all land-based life depends. And when it loses its structure and composition,  it hampers the entire ecosystem.

Pollutants present in the air like nitrogen oxides and sulphur dioxide combines with water present in the air and comes down as acid rain. As its name carries, the water from this rainfall is acidic in nature. When this reaches the soil, a lot of essential nutrients gets dissolved. A soil deprived of nutrients leads to low crop growth rendering a barren land. Barren land is of no use other than disposing of wastes.

Effects of Soil Pollution

We, as an individual sometimes fail to understand the effect that soil pollution has in our daily lives. Polluted soil means stunted crops or even toxic underground water table. We fail to understand that we are creators and destroyers of our own selves. Some major effects of soil pollution are listed below.

1. Effect on Health of Humans

Soil, being the reason for our survival, the contamination of it has major health consequences. Crops and plants are grown on polluted soil absorb much of the pollution and then pass these on to us. Prolonged exposure to such soil can affect the genetic make-up of the body, thereby causing congenital illnesses and chronic health problems.

It can also sicken the livestock to a considerable extent and cause food poisoning. Soil pollution also leads to widespread famines and barren lands if the plants are unable to grow in them.

2. Effect on Growth of Plants

The balance of an ecosystem gets affected due to the widespread contamination of the soil. Most plants are unable to adapt to the change in soil chemistry in a very short period of time. Microorganisms like fungi and bacteria that bind the soil together decline. This creates an additional problem of soil erosion.

3. Decreased Soil Fertility

Soil pollution reduces the amount and quality of harvests. This jeopardises the world’s food security. The toxic chemicals present in the soil decreases soil’s fertility which consequently leads to a decrease in soil yield. The contaminated soil is then used to produce fruits and vegetables, which lacks quality nutrients. These may also contain some poisonous substances and pose a threat to the health of the people consuming them.

4. Toxic Dust

The emission of toxic and foul gases from landfills pollutes the soil. This poses a serious health issue for people. Besides, the unpleasant smell also causes inconvenience to the people residing nearby.

5. Changes in Soil Structure

Extensive use of pesticides and chemical fertilisers leads to the death of many soil microorganisms (e.g., earthworms). This results in the alteration of the soil structure. Apart from this, it could also force other predators to move to other places in search of food. An increase or decrease of the pH content in the soil greatly hampers plant growth and productivity. In due course of time, the soil becomes barren.

6. Poisoning of Underground Water Table

The underground water table is also poisoned by soil pollution. Since this water is stored beneath the layers of the soil, the toxins in the soil could easily percolate slowly and steadily into the water table.

The water we get through wells and tube wells is this polluted water. Over prolonged usage of such toxic water causes a lot of health issues. Over a period of time, diseases like arsenic poisoning, food poisoning and others are caused due to the consumption of this toxic underground water.

Ways to Reduce Soil Pollution

Plenty of time and resources need to be pitched to curb the current rate of pollution. Strict regulations have been given to industries for the disposal of hazardous waste. Natural and organic methods of farming are being encouraged, which do not use chemical-laden pesticides and fertilisers. Plants are being used to remove pollutants from the soil. Some of the ways are:

1. Green Agriculture

Organic manure is harmless and one of the best sources of nutrients for the soil. It adds essential nutrients to the soil and restores its health. It contains no harmful by-products that could harm the soil or the environment in any way. While chemical fertilisers enhance the fertility of the soil, excess of it actually poisons the soil.

It does more harm than good. The excess of chemical fertilisers disturbs the pH levels of the soil. It kills the good microorganisms present in the soil. The surface runoffs from such soils also cause water pollution affecting aquatic plants and animals.

2. Sustainable Forest Management

1. Conservation of the forests is key to solve soil pollution. Without trees, the land becomes dry and starts to erode. Therefore, sustainable forestry or logging is crucial to saving the soil from pollution. It is quite obvious that with the ever-blooming population, humankind needs more and more space to expand. This is often achieved at the cost of the health of the soil. Reforestation of a deforested area is being promoted.
2. Afforestation should be encouraged in barren lands. The roots of the plants bind the soil particles together and even capture good microorganisms in the soil. It also ensures the maintenance of the underground water table.

3. Proper Waste Disposal

1. One of the most effective ways of curbing land pollution is the efficient disposal of waste, be it industrial or household. This especially applies to toxic and hazardous disposal of waste. Properly recycling batteries, eating sustainable foodstuffs,  producing homemade compost and disposing of drugs in the authorised places are some of the ways by which we can dispose of waste efficiently.

4. The “3 R’s” Rule & Education

We need to reduce the use of non-biodegradable products. This will lower plastic pollution and eventually have an impact on land pollution. Therefore it is very important to reuse and recycle every possible item. In present times, plastic forms a significant portion of the generated solid wastes. To get rid of this, these wastes are generally buried in landfills.

1. In landfills, the slow decomposition of plastics releases toxic substances. These substances are very harmful to the health of the soil and are a major source of soil pollution.
2. Reusing and recycling things ensures that lesser wastes are dumped in the landfills, which in turn, would reduce soil pollution.

5. Get the Locals Involved

A problem like soil pollution requires every individual’s involvement. Things will work out better only when we realise our responsibility at the individual level. Awareness programs could be designed so that people understand soil pollution better. If people are aware, they will help even subconsciously.

Summary

Environmental pollution is a burning topic in todays modern times. Air, water and soil are being polluted alike. Soil is a “universal sink” that bears the greatest burden of environmental pollution. Soil is a non-renewable resource. Its degradation is rapid, and it takes several thousands of years to form and regenerate.

The sooner we realise, the better we will be able to solve the problem. It requires everyone, from an individual to the government, to work in complete unison. It is the need of the hour that we all realise how important soil is for us.

FAQs on Soil Pollution

Let’s look at some commonly asked questions about soil pollution:

1. What are the causes of Soil Pollution?
A: The main reason the soil becomes contaminated is due to man-made and natural waste triggered by various activities such as sprinkling pesticides in the soil, plastics, biological waste and toxins, industrial waste, acid rains, etc.

2. What are the effects of Soil Pollution?
A: Some of the effects of contaminated soil are – famines, contaminated food items, health hazards, decreased soil fertility. 

3. What is Soil Pollution?
A: Pollution affects more than just the air we breathe or the water we drink. When we talk about pollution, what comes to mind first is air pollution and water pollution, but soil pollution is an equally concerning phenomenon that affects the fruits and vegetables we consume every day and deteriorates groundwater quality as well. The pollution in the soil gets to us directly, as we consume these fruits and vegetables. When the soil is contaminated by natural or man-made pollutants, it is called soil pollution.

4. How does Soil Pollution affect human health?
A. Soil is an important source of heavy metals in crops and vegetables since the plants’ roots can absorb these pollutants from the soil and transfer them to seeds. Prolonged exposure to landfill sites and dumping areas can lead to headaches, nausea and many other problems.

5. How can we avoid Soil Pollution?
A. Soil pollution can be avoided by reducing, reusing and recycling waste, switching to organic options, cleaner means of industrial production, green manuring.

Now that you have a detailed article on Soil Pollution, we hope you study well. If you face any difficulty in your preparation, do let us know about it in the comments section below and we will get back to you soon.