Hope in the soil?

Soils - living in symbiosis - a model for society

Grounded

The Soil is the ‘base’ of our life: it reminds us that it is important to ‘keep our feet on the ground’ and that we only eat by ‘putting our hands in the mud’. Soil specialist Marc-André Selosse calls this soil "the origin of life »[1]. We have a little forgotten about it. We can grow tomatoes without any soil, create meat in vitro.

Our reality has also become anxiogenic. And many of us are fleeing it. We take drugs with the complicity of our doctor or by living only in the ‘meta’ on Insta or TikTok where we create from scratch a personality that we pass for us, or by participating in Telegram groups co-opted to stop being in the ‘mainstream’ which is too scary.

But the Earth reminds us when it trembles, when it becomes barren and dry … Without Gaïa, without mud, rot and microbes, life disappears. And without blood, sobs, suffering, none of us is born.

So, what’s the soil ?

It is both the support and the product of life. It is the support of life in the sense that it brings nutrition and water. It is also the product of life, since it is formed by life from the mother rock and the detritus of plants, fungi, bacteria, animals (dead bodies and leaves, excrement, etc.). What is more, the soil is full of life, ‘is’ life; it contains more than half the living biomass on earth. Technically, the soil (the Pedosphere) is the layer of the Biosphere at the interface between the Lithosphere and the Atmosphere, simply said: the soil is the layer between the rocks and the air.

Difficult beginnings

Merlin Sheldrake, an English biologist who specializes in life in the soil, sums up the beginnings of life on Earth, saying, “About 600 million years ago, green algae began to leave shallow stretches of fresh water to settle on land. These algae are the ancestors of all terrestrial plants. The appearance of plants transformed our planet and its atmosphere, and this was one of the fundamental transitions in the history of life, a real break in biological innovation.”[2] .

But before this was possible there were already bacteria and fungi that by an ingenious process managed to 'digest' the rock from the outside.

When the algae arrived on land, their survival was compromised as the climate was dry and the solar rays (UV in particular) powerful. They created the first 'partnership'; algae, fungi and bacteria came together to form a new form of 'symbiotic' life. They were the first lichens. Lichens are organisms that can survive in extreme conditions. They are said to be extremophile. These lichens, together with the bacteria already present, formed a thin layer of soil by decomposing the source rock (thus creating fine mineral material) and being decomposed by other bacteria (thus creating organic material).

To stay still close to the rocks, these have been, and still are, broken down by·

• the action of water (by a mechanical process; infiltration of water that freezes and thaws and thus 'breaks', ‘cracks’, the rock - and by a chemical process with the acids that are in the water and that dilute the rock)·

• bacteria (by digestion 'from the outside' using an oxidizing process)·

• lichens (chemically by excreting acids - and mechanically by introducing filaments into the cracks of the rock)·

• by the mechanical action of the rootlets of the first plants

An ever faster process

Once the small layer of soil is in place, plants can grow. These plants will, through photosynthesis, create oxygen. This allows the emergence of animals.

An ever richer 'ecosystem' follows;

• plants, fungi, insects and other animals live there

• they feed on each other they help each other (through the symbiotic relationships we have already seen above)

• plants also create (prodce) oxygen (which animals that live on the ground breathe) and sugars and carbon (which they need themselves but which also benefit mushrooms or other nearby plants)

• all kinds of organisms deal with the decomposition of the organisms when they die they transform the dead organic matter into mineral molecules that plants need to feed on (nitrogen, nitrates, ...) and gaseous molecules (including oxygen) for breathing of other small aerobic animals that live in the soil

• it also creates an ever thicker soil layer and

• .... a carbon stock (which is no longer in the air, slowing down global warming)

A few more words on 'partnerships'

71% of plants have developed forms of endomycorhizes; this is an association of plants with glomerromeycetes (a family of fungi). Here, the fungus is found 'inside' the root (endo-, Greek endon = in) and makes its hyphae branch out to look for nutrients instead of the plant roots

2% of plants have developed symbioses of ectomycorrhizal form; here the fungus does not enter the roots, but remains outside (ecto- of Greek ektos = outside). It envelops the roots and helps them by excreting auxin, a plant hormone that causes increased formation of secondary roots.

Endomycorhize is a very effective form of 'partnership' that makes it possible to look for nutrients for the tree/plant in places where it has difficulty developing its roots. But the fungus (mycelium) can also look for phytosanitary products (antibiotics and other 'drugs' that the tree may need). And, may be unexpected, but the fungi can also depollute the soil (they can even absorb/transform hydrocarbons, pesticides, and radioactivity).

Soil is a reservoir of biodiversity

Finally, there is a significant presence of life. It can be said that the soil is alive. It consists of many nested spatial structures that allow the coexistence of many organisms of very diverse sizes. This makes the soil a unique reservoir of microbial, animal and plant biodiversity. It is also called 'living organic matter'. “All of these build relationships of mutual aid, struggle or predation and parasitism – in fact, it is a complex ecosystem. Moreover, the terrestrial ecosystem is above all… the soil. Its food chains born of microbes, end up on the surface of the soil, where moles, rodents and birds pecking worms crown…” [4].

The soil thus represents 26% of the known biodiversity (but we know only about 1% of soil organisms) and 50 to 75% of the living biomass.

Hope

1. Soils have been enriched over millions of years and are home to much of life on Earth. So we cannot 'create' soils. However, we can take care of them and improve them, by bringing organic matter (biomass). If we do so, we also participate in carbon storage in the soil and thus fight against global warming.

2. Soils feed plants and animals (and thereby us).

3. Some life forms that we find in the soil (bacteria, fungi) are able to depollute soils. Some plants also can decontaminate (remove heavy metals for example).

We have seen that there are forms of 'partnership' in the soil, 'symbiotic' life forms. These symbioses have allowed life under extreme conditions. They have also allowed fungi to survive several mass extinctions on Earth. Wouldn’t this represent a 'model' for a resilient society?

[1] ‘L’origine du monde. Une histoire naturelle du sol à l'intention de ceux qui le piétinent’, Marc-André Selosse, Eds. Actes Sud, Paris, 2021

[2] ‘Le Monde Caché. Comment les champignons façonnent notre monde et influencent nos vies’, Merlin Sheldrake, Eds. Pocket, Paris 2021, p 175

[3] See the book of  Marc-André Selosse (Selosse 2021), more especially the chapter ‘La vie palpitante du sol’, p 91 - 117

[4] Selosse, 2021, p 117