When we hear the word biodiversity, most of us think about plants, birds, reptiles, and mammals—soil organisms don’t usually cross our minds. And when we do make an effort to actively think about these organisms, we often limit them to ants and earthworms. However, soil biodiversity goes way beyond these invertebrates. In fact, did you know that soil comprises 25% of the world’s biodiversity?

If you want to know more about these overlooked organisms, keep on reading. In this article, we will explore their importance and the threats they face.

What is soil biodiversity?

According to FAO (Food and Agriculture Organization of the United Nations), soil biodiversity is “the variety of life belowground, from genes and species to the communities they form, as well as the ecological complexes to which they contribute and to which they belong, from soil micro-habitats to landscapes”.

Soils are a complex system which involve biotic and abiotic elements, such as nutrients, minerals, organic matter and living organisms. This system is one of the main reservoirs of biodiversity on the planet. In fact, it is estimated that a teaspoon of soil contains approximately 50 billion microbes.

Soil communities can vary across different volumes and soil types, and they form hierarchical systems. These include three broad groups:

• Microorganisms and microfauna;
• Mesofauna;
• Macrofauna and megafauna.

Each group plays a unique role in the soil ecosystem. Soil microorganisms (i.e. bacteria, archaea and fungi) and microfauna (i.e. protozoa and nematodes), are responsible for transforming organic and inorganic compounds into forms that are accessible to plants and other organisms through processes such as the decomposition of organic matter and nutrient cycling.

Mesofauna (i.e. mites, springtails and small larvae), alongside other groups, are essential in the food web, enhancing the availability of energy and nutrients, especially nitrogen.

Soil macrofauna (i.e. earthworms, ants, beetles and termites) and megafauna (i.e. some mammals and reptiles) are known as ecosystem engineers. They modify soil porosity, water and gas transport and bind soil particles together, which reduces soil erosion.

Why is soil biodiversity important?

Studies show that life below-ground has a direct effect on life above-ground—this is especially true when it comes to vegetation, since plants interact with more belowground biota than aboveground species.

Soil organisms are responsible for a number of ecosystem services, which have environmental, economic and healthimplications. Let’s take a closer look at the contributions of soil organisms in three different areas—agriculture, human health, and climate regulation:

Agriculture

The link between crop production and soil quality is well known. Healthier soil is more fertile and more resilient to climate-related hazards. As a result, crops grown in healthy soil produce greater yields with higher nutritional values. But where does soil biodiversity come in?

Soil microorganisms play a direct role in the Carbon (C) and Nitrogen (N) cycles, which means they can transform these nutrients in a way that makes them available to plants. Through their role in the carbon cycle, soil organisms increase the carbon content of soil, thus increasing soil fertility and improving soil structure, which results in better water infiltration and retention and makes soil less prone to erosion. In addition, soil biota also provides other nutrients required by plants, such as phosphorus and zinc.

Beyond nutrient availability, soil biodiversity also increases crop resilience. Soil biodiversity can be used in biocontrol, which increases ecosystem functioning and naturally reduces pests such as harmful insects, mites, weeds, and plant pathogens, thus minimizing dependence on synthetic fertilizers and pesticides.

Human Health

Some might think of soil microorganisms as a threat—a source of diseases for crops, animals and humans. However, studies have shown that these creatures can help us protect and improve our health.

Soil biodiversity can help boost the nutritional value of our food and enable plants to produce beneficial phytonutrientssuch as antioxidants. Consuming plants that are high in antioxidants and other nutrients improves our immune system, hormone regulation, and overall health. Thus, soil biodiversity results in healthier diets and healthier people!

In fact, emerging research suggests that early exposure to soil biodiversity may help prevent inflammatory diseases, such as allergies, asthma, and autoimmune diseases. Moreover, soil biota is also used in the production of medicines (e.g. antibiotics) and vaccines.

If you want to learn more about the connection between human health and soil biodiversity, make sure to read this article.

Climate regulation

Soil creatures play a key role in climate regulation, contributing to both the reduction of greenhouse gas (GHG) emissions and to carbon capture and storage.

Agriculture is responsible for 10% to 12% of all anthropogenic GHG emissions each year, mostly due to the use of synthetic fertilizers, poor land management practices, methane release by ruminants and manure storage. By improving C and N availability, soil organisms can reduce the demand for GHG-emitting synthetic fertilizers in agriculture. And when fertilizers are applied, these organisms can transform the nutrients in a way that reduces their volatilization, thereby decreasing GHG emissions.

In addition, soil biodiversity is essential for soil carbon sequestration, a process that captures carbon from the atmosphere and stores it in the soil for hundreds of years. This is especially important for climate change mitigation, seeing that healthy soil can store more carbon than the atmosphere and vegetation combined.

Anthropogenic Threats Faced by Soil Biodiversity

There are still some gaps in knowledge when it comes to the system below-ground—it is estimated that only 1% of soil microorganism species are currently known. And more and more studies are demonstrating just how complex the soil food web is and how the suppression of just one species has a cascading effect on other trophic levels within the web, jeopardizing ecosystem functioning and life above-ground. That goes to show how important it is to pay attention to these creatures that are out of sight and usually out of mind.

Human activities pose a huge threat to soil biodiversity and the ecosystem services they provide. Let’s dive deeper into some of these threats:

Agricultural intensification

Agricultural intensification has negative effects on biodiversity above and below-ground. Conventional, large-scale agriculture typically adopts destructive soil management practices and depends heavily on harsh chemical inputs, including fertilizers and pesticides.

These agrochemicals harm soil organisms and soil function. For example, Potassium Chloride (KCl), a commonly used synthetic potassium fertilizer, contains high concentrations of chloride, a biocidal ion that causes the death of soil organisms. Pesticides also cause the loss of soil biodiversity, as they can affect a restricted class of organisms or a broad spectrum, meaning they might kill not only “bad” organisms, but also some of the “good” ones.

Soil biota is also threatened by some soil management practices, such as tillage. This practice alters soil properties, including soil organic matter (SOM) and nutrient availability. It also directly harms organisms by killing, injuring, or exposing them to predators. Production of large-scale monocultures is also detrimental to soil biodiversity, as it limits the presence of beneficial species of bacteria, fungi and insects.

Climate Change

As mentioned previously, soil biodiversity can help us fight climate change; however, rising temperatures can lead to a loss of soil biodiversity, creating a bit of a Catch-22.

The excess CO2 in the atmosphere increases photosynthesis, thereby increasing the demand for nutrients. In turn, this intensifies competition between organisms and plant species for resources.

Furthermore, climate change aggravates extreme weather and climate-related disasters, including heavy rainfall, severe droughts, wildfires, desertification, and increased fluctuations in seasonal temperature. All the mentioned examples pose a threat to soil biodiversity, whether directly or indirectly. These events change soil biotic and abiotic conditions, which jeopardize soil biota – for instance by causing water restrictions or oversupply, loss of SOM and nutrients, and reductions in above-ground vegetation to name a few.

Salinization

Soil salinization is the accumulation of salts (or ions) in soil, leading to negative impacts on environmental health and agricultural productivity. Salinization can occur naturally or due to anthropogenic activities, including overuse of fertilizers and certain irrigation practices.

High salt concentrations result in nutrient deficiency and a smaller and more stressed microbiological community. Salt exposure impairs organisms’ vital functions, such as respiration and growth, leading to their death. This is true even in salt concentrations considered safe for plants. Therefore, salinization jeopardizes the overall biological diversity of the ecosystem.

If you want to learn more about the negative effects of soil salinization, make sure to read this article.

How can we protect soil biodiversity?

If you want to help protect soil biodiversity, but don’t know the best way to do it or how to get involved, here are some ways you can help these organisms thrive:

• Support scientific research:

As mentioned previously, although there has been a great deal of new research on soil biodiversity, there are still gaps in knowledge when it comes to these creatures. Scientific research is of the utmost importance if we want to put an end to the climate crisis. Support scientists by funding their studies or sharing their work.

• Support initiatives

There are initiatives, like the Chloride Free Foundation, that are working to promote soil health and protect soil biodiversity. You can support our work by making a financial contribution, volunteering some of your time and skills, or sharing our work.

You can also sign and share our petition to make agriculture chloride-free by 2040.

• Support businesses

Sustainable farming is essential if we want to protect life below and above-ground, including ourselves. Farmers are key actors in promoting soil health and biodiversity, but they also need help. You can support farmers in adopting sustainable practices by choosing where you put your money. While grocery shopping or just buying your daily cup of coffee, choose natural products that meet sustainability standards.

• Talk about soil biodiversity

Not a lot of people know what soil biodiversity is and the diverse and significant roles these organisms play. We need to shed light on their existence and their importance in this big ecosystem we call Earth. You can do that by talking to your friends and family, promoting educational events or sharing educational content (like this article) on your social media.

Do you know any other actions that people can take to promote soil biodiversity? Tell us in the comment session!

Below there are some other articles that you might be interested in:

• Organic Fertilizers: The Best Alternative to Chloride Containing Fertilizers
• Sustainable Farming and its Relationship with Soil Biodiversity
• Soil Bacteria: The Building Blocks of Healthy Soil

This article was originally published here