Soil degradation: the problems and how to fix them

Dhaka, 20 April, 2021: A third of the world’s soil is moderately to highly degraded, threatening global food supplies, increasing carbon emissions and foreshadowing mass migration. A change in farming practices has never been more urgent.

Soil is a priceless, non-renewable resource that's home to thousands of animals, plants and other important organisms. It supports countless ecosystems and provides us with essential food and resources. The dirt beneath our feet often goes unnoticed but it is key to sustaining all life on Earth.

Silvia Pressel, a Museum researcher in the Algae, Fungi and Plants Division, says, 'Soil is full of millions of living organisms that interact with one another. These organisms have a major influence on soil, such as its formation, structure and productivity.'

What is soil degradation?

Soil degradation describes what happens when the quality of soil declines and diminishes its capacity to support animals and plants. Soil can lose certain physical, chemical or biological qualities that underpin the web of life within it.

Soil erosion is a part of soil degradation. It's when the topsoil and nutrients are lost either naturally, such as via wind erosion, or due to human actions, such as poor land management.

What does healthy soil look like?

There are many types of soil around the world. The UK alone has over 700 varieties, such as clay, sand, silt, loam and peat. These soils have different characteristics which can be useful for humans.

Healthy soil has a good combination of soil structure, chemistry, organic matter content, biology and water permeation for its type.

A typically healthy soil will be teeming with biodiversity and may include a variety of earthworms, 20-30 types of small arachnids, 50-100 species of insects, hundreds of different fungi and thousands of bacteria species.

'There are some things in soils which will be visible to the naked eye, like invertebrates and plant roots,' explains Silvia. 'But there are also millions of things people won't be able to see like micro-organisms and all the fascinating work they do together.'

Nowhere else in the world is nature so densely packed. A teaspoon of soil can contain more organisms than there are humans living on Earth.

A type of mycorrhizal fungi forming a symbiotic relationship with a plant root. These fungi help plants absorb hard-to-get soil nutrients, such as phosphorus in exchange for sugar. Mycorrhizal fungi are ubiquitous on land, but are being destroyed by farming practices such as tilling and use of chemicals. Research on mycorrhizal fungi is increasingly important and could be a viable solution for sustainable agriculture. Image by Ellen Larson/wiki (CC BY 2.5).

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One of the most widespread soils in Britain is brown earth, which covers about 45% of land in England and Wales.

Brown earth has a deep top layer where most of the nutrients are and biological activities take place. At around 20 centimetres deep, it provides a lot of space and encouragement for roots to grow comfortably.

Brown earth also drains water at a moderate rate, which allows plants to absorb enough water without drying out or flooding.

These qualities make brown earth well-suited for agriculture, and most British farms depend on it.

The benefits of soil

The millions of organisms that live within soil interact with one another and contribute to a number of cycles that make all life on Earth possible. These include carbon, nitrogen and phosphorus cycles.

Soil plays a vital role in cleaning water. Minerals and microbes filter and buffer potential pollutants, some of which are absorbed by soil particles. This is promoted by the thousands of organisms that live in soil, including earthworms, ants and termites, which create channels and routes for water and air to flow through.

Soil also regulates the movement of water and prevents floods by controlling whether rainfall, snowfall and irrigation water will flow over land or through it.

Healthy soil contains high biodiversity, which helps fight off pests and allows fresh, nutritious plants to grow.

Soil also contains organisms that can kill harmful bacteria. A variety of medicines have been made from organisms that live in soil, such as penicillin – a group of antibiotics widely used to fight off bacterial infections.

Soil provides physical stability for plants by allowing the roots to anchor to something. This in turn helps create oxygen and clean water for all life on Earth. Soil also provides support for manmade structures, including treasured but fragile archaeological sites.

Finally, soil plays a very important role in mitigating climate change. It is the second-largest carbon sink after the ocean, constantly storing and releasing carbon, which regulates atmospheric CO₂ concentrations and, ultimately, the greenhouse effect. 

Peatland landscapes vary from frozen, open spaces in Scotland to swamp forests in Indonesia. Peatlands are the largest natural form of carbon storage on land and are vital for reducing global carbon emission. Due to lack of awareness, many peatlands have been overexploited and damaged by draining, burning and mining. Image by Ross/wiki (CC BY-SA 2.0).

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The cause of soil degradation and how it affects us

Soil is not an inert medium but a living ecosystem that is essential to life. It takes hundreds and thousands of years to form an inch of topsoil, and many more centuries before it is fertile.

While soil degradation is a natural process, it can also be caused by human activity. In the last few decades, soil degradation has been sped up by intensive farming practices like deforestation, overgrazing, intensive cultivation, forest fires and construction work.

These actions disturb soil and leave it vulnerable to wind and water erosion, which damages the complex systems underneath.

Silvia says, 'Several practices associated with intensive agriculture, especially tilling, disrupt soil structure. They accelerate surface runoff and soil erosion, loss of organic matter and fertility and disruption in cycles of water, organic carbon and plant nutrients. These practices also have a major negative impact on soil biodiversity.

'When soil degrades, the processes that take place within it are damaged. This causes a decline in soil health, biodiversity and productivity, leading to issues at all levels of many ecosystems, and resulting in large environmental consequences such as floods and mass migration.'

When natural land such as a forest is converted into farmland, it removes important nutrients and prevents the recycling and replenishing of organic material.

It also reduces the amount of carbon the soil can store by 50-75%. With global warming being one of the biggest environmental crises of our time, this would be a giant step backwards.

Soil compaction occurs when there is a combination of wet soil and a heavy weight, for example unwieldy machinery in farming. Networks of tunnels and pores created by various organisms collapse beneath the pressure and air is squeezed out, threatening underground habitats and the availability of nutrients. Tilling soil also has similar results.

Salination – salty water – is a result of excessive irrigation or extraction of groundwater in coastal areas. This can make some bacterial species inactive and can kill many other microorganisms.

Without underground life, land would become barren. In a worst-case scenario, it can lead to desertification, where the soil is damaged beyond repair and nothing grows except a handful of plants that can handle very harsh conditions.

But it's not just agriculture that is to blame: increasing urbanisation also has a negative impact. The widespread use of tarmac and concrete prevents water from being absorbed into the ground. This results in the death of millions of microorganisms and can lead to water runoff in other areas where it may cause flooding and erosion.

Soil degradation can have disastrous effects around the world such as landslides and floods, an increase in pollution, desertification and a decline in global food production.  One of the biggest threats to our future food security is land degradation and the associated loss in soil productivity. 

Areas that are most likely to be affected are developing countries which usually provide services and materials to middle- and high-income countries. Many of the people who live in low-income countries could be forced to leave their homes in search of safety and fertile lands, resulting in the loss of cultural identity as well as possible economic and political instability in other areas.

Acknowledging soil for what it is and recognising the irreplaceable role it plays can help us change the way we care for it which is something that needs to happen now.

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Posted by admin on Apr 20 2021. Filed under Forest & Land, News at Now. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry