The soil is a crucial component of agriculture and forestry, and degradation leads to a partial or total decline of its productive capacity. Due to natural hazards or human mismanagement, the soil can lose one or more of its potential ecological functions, leading to a steep decline in its capacity to be used in the production of goods and services.
Defining Soil Degradation
A 2004 report by the U.N. Department of Economic and Social Affairs described soil degradation as a process that occurs when “the balance between the attacking forces of climate and the natural resistance of the terrain against these forces has been broken by human intervention, resulting in a decreased current and/or future capacity of soil to support life”.
Soil degradation is primarily attributed to mismanagement or misuse of the land in domains such as agriculture, industry, or urban planning. Due to its major impact on food growth and consumption and on the environment as a whole, soil degradation causes have been a constant topic of research and concern throughout the 20th and the 21st centuries.
Causes of Soil Degradation
Throughout the world, soil degradation is usually caused by one or more of these three factors:
factors represent the loss of the soil’s life-sustaining qualities
due to natural physical forces, mainly water or wind erosion. These
physical forces affect the structure of the soil mainly by damaging
its top layer and subsequent organic matter, where the nutrients
necessary for sustaining growth are found. Long-term exposure to
massive rainfall, winds, floods, surface runoff, or any other
powerful physical factors leads to the slow decline in the
respective soil’s structure and quality. According to Volume 11 of
the publication “Advances in Soil Science,” physical
degradation can include:
- Compaction and hardsetting, causing densification of soil due to the elimination or reduction of its structural pores, and also increasing soil’s bulk density as a result of natural and manmade factors.
- Desertification caused by erosion and sedimentation due to constant exposure to wind and water.
- Laterization, meaning the desiccation and hardening of plinthitic material.
- Chemical factors are the alterations of the soil’s chemical properties that lead to it losing nutrients. University of Chittagong professor Khan Towhid Osman’s book, “Soil Degradation, Conservation and Remediation,” states that chemical degradation of soil can be caused by a number of factors, such as a rise of alkalinity or acidity levels, or simply the oversaturation of the respective soil with water. The result is usually either a buildup of salt or the hardening of the soil, with soil nutrients being irreversibly lost in the process. More than half a billion acres of land are affected by chemical soil erosion throughout the world.
- Biological factors refer to human activities or plant growth that cause degradation of soil quality by accentuation compaction, erosion, water runoff, anaerobiosis, nutrient depletion, reduction in SOC pool etc., as described in the book “Soil Degradation in the United States: Extent, Severity, and Trends.” An overaccumulation of fungi or bacteria can, for example, cause biochemical reactions that will drastically reduce the soil’s capacity to grow proper crops. Poor farming practices and overfarming also have the potential to diminish the fertility of the soil by depleting it of nutrients. These farming practices can be excessive cultivation, improper manuring, misuse or overuse of fertilizers, or excessive irrigation, among others.
There are also other factors that can lead to soil degradation. Deforestation will dramatically alter the soil’s composition by removing the vegetation that binds it together. Mining and other industrial activities release toxic substances into the soil, making it poisonous and completely unusable. Also, urbanization will unavoidably affect the soil quality by covering the soil with concrete and with the inevitable rise in pollution levels.
Effects of Soil Degradation
The most significant effect of soil degradation is the loss of a land’s life-sustaining qualities. Throughout the world, more and more land becomes unusable because of factors like soil pollution, contamination, and erosion.
The overuse of fertilizers also keeps the affected land from regenerating, polluting both the land and water in the area and dramatically decreasing land value.
Another major effect of degradation to the soil is its contribution to droughts and the occurrence of arid conditions in certain areas. Soil degradation reduces the biodiversity in the area, leading to desertification and the inevitable drought and aridity that come with it.
The University of Sheffield’s Grantham Centre for Sustainable Futures estimates that approximately 40 percent of the world’s agricultural land is unusable because of the loss of soil quality caused by degradation and overuse of agrochemicals. These practices make agriculture impossible, and therefore make the respective land useless.
Due to the alteration of the degraded soil’s physical attributes, one of the consequences is the affected land’s inability to hold massive amounts of water, leading to increased chances of floods occurring.
How Big is the Range of Soil Degradation Observed Between Continents?
Soil degradation is a big issue all over the world, but Africa is by far the most-affected continent. Throughout the African continent, it is estimated that 28 percent of the land is affected by degradation.
This costs the continent as much as 56 billion euros every year. It’s usually manmade, with the lack of fertile land being compensated by mass deforestation, leading to massive soil degradation. It can be reversed, though, with massive state programs and policies that train communities to take better care of the land.
Other areas of the world gravely affected by the degradation of soil are Southeast Asia, Northern and Central Australia, China, and parts of the boreal forests in North America and Siberia.
Solutions for Soil Degradation
The reduction and reversal of soil degradation typically lie in the elimination of manmade causes. Chief among these causes is massive deforestation, and the trend can be reversed by educating populations and governments about the dangers of reckless deforestation. Improving the land’s organic composition and restoring its mineral matter can also reverse soil degradation.
Prevention is also crucial to reducing the amount of land that is affected by soil degradation. Reducing over-irrigation, improving overall irrigation efficiency, and preventing land salinization are all significantly more cost-effective than restoring soil that has already been affected by degradation.
Soil degradation is an issue that affects the entire world in numerous ways. It increases the odds of famine and poverty in already impoverished countries. It also increases the cost and human labor that’s necessary to grow food throughout the world, massively influencing the price and quality of the food that we eat.
Other side effects, from dramatic rises in pollution levels to socio-economic effects like mass migration, also contribute to soil degradation’s status as a major global issue.
Advances in Soil Science Vol. 11, Soil Degradation
Soil Degradation, Conservation, and Remediation, Khan Towhid Osman
Soil Degradation in the United States: Extent, Severity, and Trends, Rattan Lal, Terry M. Sobiecki, Thomas Iivari, John M. Kimble
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