Cartoon of industrial farming showing farmers spraying non organic pest control and fertilizer into the soil.
June 9, 2023
 in 
Environment

Soil Pollution: Origins and Consequences

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oil is a mixture of dead and living organic matter, minerals, water, and gasses. It is also the foundation of all life on earth and home to an innumerable amount of microorganisms. The healthy function of soil is essential for the healthy function of earth and those that live on it. When soil becomes compromised through pollution, so do the systems that support the health, and happiness of our lives. 

The effects of soil pollution are extensive. In the last 50 years, the earth has lost over one-third of its topsoil. This has led to the displacement of millions of people, pushed off their land as a result of desertification caused by top solid erosion. Monocropping and pesticide use contribute to poor air quality. It is estimated that poor farming practices released over 4 billion tons of carbon dioxide in the first half of the 21st century. 

However, that being said it’s not all bad news. Even in a degraded state, soil has been shown to be responsible for the sequestration of over 10 percent of the world's total carbon dioxide emissions. To put that in perspective, the United States, as a whole, produces 12 percent of the world's total carbon dioxide emissions and is the second largest producer behind China. 

Having healthy soil can lead to cleaner and more nutrient rich food, the slowing down of desertification, and thus an overall healthier population. Learning about  the impacts of soil pollution is essential to understanding the value of growing our own produce, buying from smaller or organic farms, composting, recycling and much more.  is essential to building more sustainable communities and better quality of life. 

Table of  Contents

What is soil pollution

Soil pollution is the addition of inorganic and,or toxic organic matter to soil that results in the degradation of the quality of the soil. The majority of soil pollution is caused by human activities such as mass farming, industrial and urban waste, deforestation, and radioactive dumping.

1 cubic square foot of soil contains more microorganisms than the number of humans who have ever lived on earth. Unfortunately, it doesn’t take much to wipe out that thriving and essential population of organisms.

When we add pollutants to the soil, we greatly reduce our ability to produce healthy food, process air pollution, and even compromise the health of our oceans–the biggest resource for life on earth.

How? 

Well, it all goes back to the water cycle. When soil becomes heavy with pollution, its ability to absorb water and additional pollutants decreases. This saturation leads to substantial release of these pollutants into the air, and runoff which is a mixture of water and pollutants from the soil and other sources.  

The release of soil pollutants into the air contributes to acid rain that leads to further acidification of soil and water. While runoff carries toxic chemicals and pollutants with it into streams, lakes,and rivers that all eventually dump to the ocean. 

While it may seem strange that ocean pollution is connected to the quality of our soil, consider that 60% of the freshwater we have on land comes from our oceans. Industrial farming agents such as pesticides, herbicides, and insecticides contain substantial amounts of heavy metals, nitrates, potassium and calcium chloride that get washed into the ocean. (You can learn about water pollution here). 

The increase in the concentration of these chemicals lead to the growth of larger algal systems that increase the nutrient load in the oceans leading to oxygen consumption and the enlargement or creation of more dead zones (parts of the ocean where life is no longer supported due depleted oxygen concentration). 

Deforestation is also a large contributor to soil pollution. Cutting down trees degrades the upper nutrient rich layer of soil in turn leading to a weakened ability for it to support other plant and animal life. 

Causes of soil pollution

One big gray heap of trash and waste isolated on white, with mountains of trash and waste bags, environmental pollution illustration

By definition, soil pollutants are substances that exceed naturally occurring levels and pose a health risk to humans. Common soil contaminants can include pesticides, herbicides, fertilizers, lead, oil, and asbestos. These chemicals can be left behind by manufacturers, farmers, or even the everyday person with an oil leak. 

Industrial Agriculture

The industrialization of agriculture has resulted in an increase in soil pollution by the industry that relies on soil itself. Many farmers practice growing the same crop on the same plot of land for many years. This practice–called monocropping–strips the soil of the essential nutrients like nitrogen, phosphorus, and potassium. Farmers then have to use synthetic fertilizers to replenish these macronutrients to sustain arable soil.

The addition of synthetic fertilizers decrease the natural micro-biodiversity of the soil making the crop less resilient. The crop then becomes more susceptible to fungus, pests, and other types of harmful pathogens. Farmers are then forced to use pesticides, herbicides, and antifungal chemicals to support the plant in reaching full maturity. 

These harmful chemicals then collect in the soil, further compromising the quality of the soil and thus requiring more fertilizers, pesticides, and synthetic chemicals to produce viable crops. 

This cycle has caused a major uptick in the amount of chemicals needed to grow even a single bushel of wheat. Farmers are requiring 3.5 times more pesticide to grow a single bushel of wheat than they were 50 years ago. 

Manufacturing Industry

Whether it's building houses or textiles, the manufacturing industry is one of the biggest culprits of soil pollution. The type of contamination that accumulates in the soil surrounding industrial and manufacturing sites can vary. 

Most soil pollution occurs as a result of disposing industrial waste directly into the ground. Sewage, sludge, and chemical leaching from manufacturing plants can cause a build up of toxic chemicals in the soil. The most common chemicals include lead, nickel, zinc, and cadmium. These heavy metals can lead to health problems like cancer and the phytotoxicity of plants, further complicating the production of crops 

Urban Waste

Landfills, highway corridors, house construction, and heavy traffic are just a few threats to healthy soil in urban settings. Much of the soil found in urban areas can be contaminated with lead from paint, petroleum products, and tyre dust from nearby highways.

Major soil contaminants and where they come from 

There are four significant types of soil contaminants. Each type can have different effects on the soil; however, across the board these pollutants can cause serious health problems and contaminate the produce that is grown in the affected soil.

Petroleum Hydrocarbons

Soil contamination from petroleum hydrocarbons usually comes from the extraction and transportation of crude oil and natural gas. These hydrocarbons decrease the concentration and activity of vital microorganisms. These organisms are responsible for the very important nitrogen fixation cycle. Nitrogen fixation is a key process that involves the extraction of the inert form of nitrogen from air and its delivery to crops and plant life in a digestible form promoting healthy growth.The existing population of microorganisms do not only make nitrogen available in soil, but they do so in a balanced manner that does not result in the excess runoff into waterways that is encouraged by usage of industrial fertilizers in mass farming.

In addition to the killing of essential soil microbes, deflocculation–or soil dispersion–can cause soil to lose its structure and with this, the healthy movement of air, water and plant roots within it. This results in  a soil quality that is more susceptible to erosion and contributes to desertification.

Agrochemicals

Agrochemicals such as pesticides, insecticides, herbicides, nematicides, and fungicides can destroy soil biomass and lead to soil infertility and damage the nutrient element cycle. Increases in the agrochemical use by farmers cause an imbalance in soil chemistry and contribute to soil degradation and, ultimately, erosion. 

Heavy Metals

Heavy metals such as lead, zinc, and cadmium are often found around mining sites, metal plants, and milling plants. These organic compounds accumulate within the soil and pose a significant health risk to humans and the surrounding ecology. These heavy metals can even be absorbed by plants, fish and contaminate food and water. 

Soil pollution examples

There are two main types of soil pollution: organic and inorganic waste. Organic waste comes in the form of sewage, sludge, and garbage. Inorganic waste comes predominantly from heavy metals and is often found in industrial waste. 

Inorganic toxic compounds

Copper, mercury, cadmium, lead, nickel, and arsenic widely referred to as heavy metals are found in significant amounts in fertilizers and can accumulate in the soil. These also settle into the ground through improper disposal of waste, mine washing, or even some fungicides.

A famous–and tragic–example of inorganic soil pollution can be seen in Flint, Michigan. Here, 99,000 individuals were exposed to lead poisoning from industrial chemical leaching. The result caused widespread health problems and put thousands of people at a higher risk for Alzheimer's disease and cancer. 

Organic waste

Organic waste such as borates, phosphates, phenols, and coal are major contributors to soil pollution in urban areas. In addition to this, the improper disposal of sewage and other liquid wastes pollute the soil and cause changes in humus content, porosity, and leaching. 

Organic pollution can also lead to harmful algal blooms in waterways and in the soil. This change in biodiversity impacts the healthy function and richness of an ecosystem. 

Los Angeles county residents noticed these changes after 8.5 million gallons of raw sewage spilled into the county and contaminated the waterways. The spill resulted in illness and caused several beaches to become uninhabitable while the spill was being cleaned up. 

Effects on the environment and possible remedies

As you can see, soil pollution is a pervasive problem. The effects of soil pollution include:

Climate change

Carbon dioxide escaping from the soil into the atmosphere .

The microbiome that lives in soil, along with the plants that grow from healthy soil are responsible for sequestering a substantial amount of CO2 from our atmosphere. In the first decade of the 21st century soil degradation caused around 4 billion tons of CO2 to be released back into the atmosphere.

Water source contamination

worker is full hazmat suit collects soil in a test tube for soil analysis.

One of the biggest environmental effects of contaminated soil is the leaching of toxic chemicals into important water sources. These chemicals can then be taken up by humans, plants and animals threatening health complications on a greater scale. 

Desertification

Wide panorama of barren cracked land with sun barely visible through the dust storm.

Perhaps the most alarming of the effects of soil pollution, desertification is the degradation of fertile land into arid, semi-arid, or dry land. It is estimated that by 2050 1 billion people will be refugees of soil desertification. Currently, 40 million people are pushed off their land each year. 

Because soil is a huge factor in the sequestration of soil, the steady desertification also lowers the earth's ability to naturally capture the amount of excess CO2 in the air.

What Can Be Done?

Farmer holding healthy soil and seedling in hands.

While there is no perfect solution, we as  individuals who care about this planet can educate  ourselves and others on the issues surrounding soil pollution as a first step and use this knowledge to influence our consumption habits. 

For example we can opt to use natural pesticides and fertilizers in our own gardens to start. We could buy produce from local farms that don't practice monocropping, start opting for  more natural cleaning products, and adapt other circular consumption practices.  

Several cities have had success creating municipal composting programs, implementing fines for excessive waste, and creating large networks of community gardens. 

Regenerative farming uses a range of diverse flora and fauna that are intended for regenerating topsoil. The use of cover crops, no-till practices, and crop rotation reduces the need for fertilizers and pesticides and creates a healthy, nutrient rich topsoil.

Scientists predict that soil regeneration could result in the sequestration of a billion additional tons of carbon each year. That is enough to reasonably reverse the effects of climate change over the next 50 years. 

Having healthy soil is essential to ensuring a healthy planet. The food we eat, the water we drink, and the air we breathe are all heavily dependent on the quality of the dirt beneath our feet. Taking part in small practices like composting, shopping for farm to market vegetables, and voting for policies that prioritize the land over the crop is essential to making impactful changes in the way we prevent soil pollution.