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2020. május 18.

Know Your Roots

The history of soil contains clues to the fate of civilisations that fail to take care of their soil.

CEEweb Series: Our Common Ground (2/4)

Other stories in CEEweb's 'Our Common Ground' Series:
Part 1 - Soil: The forgotten miracle
Part 3 - One Reaps what one sows
Part 4 - The good earth

By Andreas Candido

Soil’s importance to humanity’s survival is vastly underestimated. The Mayans of Central America and the Harappan of India met their downfall because of the mismanagement of their soils. Nevertheless, humankind seems to be generally oblivious about the lessons from the past as we continue to damage our planet substantially. Therefore, the question arises: will we meet our downfall because of modern soil mismanagement?

It might seem ludicrous at first, but the soil is at the heart of every civilization’s ecosystems. It is responsible for our food and to filter our water. Our sustained damage to the soil and biodiversity is already causing problems for human health. As we continue to better understand the science behind soil, the long-term forecasts of the consequences of our actions become increasingly more worrisome.

As part of CEEweb’s mission to highlight the importance of biodiversity, especially in the wake of the global pandemic in 2020, we have decided to launch a series of articles helping to raise awareness on one of the least developed issues in biodiversity. This is the second in the series focusing on how soil, biodiversity and human’s future health are connected. This series is based on the fantastic work of the ‘Global Soil Biodiversity Atlas’*.

A single gram of soil may contain millions of individuals bacteria, including several thousand species

The magic beneath our feet

Soil is the habitat for some of the most diverse creatures on Earth. Archaea, bacteria, protists, tardigrades, rotifers, nematodes, acari (mites), collembolans (springtails), worms (enchytraeids and earthworms), microarthropods (e.g. ants, termites, centipedes, millipedes, woodlice, etc.) and burrowing mammals.; you name them. And these are just but a few of the organisms that consider the soil to be their home.

However, soil is much more than just a habitat. Its purposes range from filtering our water to providing our food — even the best china dishes are made from the soil! Soil research is linked to ecosystems, human health, environment, climate change, food security and more. It is vital to study it to understand its wider effects on humans and our planet. The soil Society of America summed it up well:

Soil provides ecosystem services critical for life: soil acts as a water filter and a growing medium; provides habitat for billions of organisms, contributing to biodiversity; and supplies most of the antibiotics used to fight diseases. Humans use soil as a holding facility for solid waste, filter for wastewater, and foundation for our cities and towns.”

Biodiversity and humans are far more linked than most people realise. The best illustration of this is how much we depend on soil. Below is a just a small list of the many ways soil, biodiversity and humans are intertwined:

  • Water Filtration: Soil is a major contributor to the natural process of decontaminating our water. Contaminants are removed through three different methods: physical capture, chemical absorption and biodegradation. Soil’s qualities mean it is an important tool in waterborne issues, which is a problem for nearly half the globe. Well designed and maintained on-site sewage treatment plants, such as septic tanks, make use of soil to deal with wastewater.
  • Food: Soil is a vital component of our food production. Many different soils are used across the globe to grow different crops. According to Nature, approximately 78% of the average per capita calorie consumption worldwide comes from crops grown directly in the soil. Quality, quantity and food security are all very important; soil plays a major role in all three.
  • Human Health: As soil is a key process in our water and food production, it is only natural that soil plays a key role in human health. That’s why the issue of soil contamination has a far-reaching impact on biodiversity and human health. Scientists have outlined how chemical contaminants in the soil can lead to a variety of health issues. Exposure to heavy metals is another major public health concern. All of these issues are widely documented and are closely linked with climate change.
  • Climate Change: Since 1850, around 35% of all greenhouse gases released are due to land usage changes. Sustainable land practices can have a significant effect on emissions levels and help restore some of the biodiversity being lost to climate change. For example, soil moisture has increased in Northern Europe and decreased significantly in the Mediterranean region since the 1950s. A further 13 countries in the EU have declared they are affected by desertification — a form of land degradation in drylands.

The evolution of soil research

Since scientists first started studying soil, we have come a long way in our understanding. The strong and sometimes unexpected ties it has with nearly all aspects of biodiversity highlight the breadth and depth of soil’s role on the planet. The history behind our discoveries is another pillar of our awareness campaign. Bear in mind, of course, that it is critical to remember that science is constantly evolving: it is a discipline that builds upon previous discoveries and, every so often, throws up discoveries that force wholesale change in our understanding. Technology and data allow scientific research to improve and go further than before. In that line, scientists have shown that the damage of climate change and land usage on biodiversity are linked with issues such as an increasing number of zoonotic diseases.

The sheer amount of different soil compositions is so vast that scientists have barely scratched the surface in their studies of organisms living in the soil.

Taxonomy is the science of defining and naming groups of biological organisms through their shared characteristics. One of the most important contributors to this branch of studies was Swedish botanist Carl Linnaeus (1707-1778) and, you guessed it right, also an important figure in the history of our understanding of soil. He was responsible for popularising a rank-based method of classifying species, which he used to classify over 10 000 species of organisms. The original ranks he proposed were kingdom, phylum, class, order, family, genus and species, although other ranks and sub-ranks have since been added. His system was the basis for which many new discoveries were made. Many scientists built off his original work, adapting and evolving his system.

From the mid 1970s, this science shifted towards comparing on the molecular level as the primary factor in classification. This change was important because previously they had been defined by their characteristics — that could be seen with the eye or with the help of a microscope. The emergence of DNA and RNA sequencing allowed researchers to discover groups that had previously been overlooked because of their differences. For example, animals, fungi and plants may not look similar but they are far more related to each other than they are with either bacteria or Archaea.

Over time, a combination of advancing technology (microscopes) and science (staining techniques) led to the identification of new organisms and a better understanding of cell structure and functioning. When Linnaeus published his classification system, there were only two kingdoms — animals and plants. Today, although there is not an exact consensus, it is largely agreed that there are six kingdoms (fungi and several different types of bacteria and microbes).

Despite the advances in science, there remain some limits in our understanding. The organisms living in soil are some of the smallest in the world and studying them can be immensely hard. Microbes are a good example — although they are by no means the only one. According to current estimates, more than 90% of microbial species remain unculturable — in other words, they cannot be grown in a lab. This means we cannot know what they look like or how they function. Nonetheless, advances in molecular techniques have led to the discovery of new culturable species and better understanding even of the unculturable ones.

Science shows us the benefits of soil and the threat to our long-term health and survival if we do not take care of our earth. Scientists may not know everything about soil, but while humans study the lifeline of most living organisms, we simultaneously understand we are doing substantial damage to it. We need to spend more time learning about the soil and what we can do to achieve sustainable practices. These goals are achievable but only if we raise awareness and, specially, tackle the threats that are.

This article is the second of the CEEweb series ‘Our common ground,’ part of a wider drive to help teach people about the importance of soil. Next week we will take a thorough look at the threats and long-term outlook of soil, before finally covering how to tackle these issues in our final edition.

*The Global Soil Biodiversity Initiative, authoring body of the Global Soil Biodiversity Atlas, aims to bring awareness and educate on the importance of soil in our daily lives. The hope is that by increasing awareness on these aspects, people will have a greater understanding of the need for rich, diverse environments to protect our way of life and our planet. The Atlas was published by the European Commission in partnership with over 20 universities and organisations. It is free for anyone to download.