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In the beginning, was the Big Bang
And, among the trillions of suns created,
In an obscure galaxy, called the Milky Way
A planet flew from a sun about 4.5 billion years ago
Consisting of rock and then water,
Life appeared within a billion years, starting in the warm seas.
Then simple animals/plants with recognisable cells appeared about a billion years ago
and sometime after that the living soil evolved, but when?
All over the world the key characteristics are the same
Although every clod is diiferent.
The main soil animals are springtails, mites, nematodes and worms
Along with the fungi and bacteria, they created the soil food web,
They were living IN the Earth long before insects arrived
It is this soil that gives the planet its name - Earth.
And which enabled all those 'Higher' plants and animals to appear
That we now wonder at and call 'Nature'.
Yet we treat this soil like dirt.
By Dr Charlie Clutterbuck PhD MSc BSc (Agric)
By Dr Charlie Clutterbuck PhD MSc BSc (Agric)
Before you start reading this story, can you answer the question: “When did the soil evolve?" Most people are surprised at the question. As if the answer - ie soil - has always been there. We take it so much for granted we dont even ask how it got here. When I asked this to 'Sense about Science' Soil - a non renewable resource, I didn't really get an answer.
And much evolutionary biology talks bout the great leap forward called 'terrestrialisation'. Yet too presumes the land is already there, when all the plants and creatures come out of the water to live life ON land. Again, as if it was there waiting for the invasion.
The Earth
The Earth
Does this question sound strange – or does it make sense to you? It probably makes more sense if you consider the soil is a 'living entity'. This 'entity' is somewhere between an organism and an ecosystem. But if it is living, when did it evolve? It must have been some date, as it was not always there. And yet now we call ourselves 'The Earth'. There were always rocks, but not always soil. I presume you consider it is more than 7 days or 4000 years ago, but is it one million years ago, ten million, 100, million, 200 mya, 400 mya or even further back – perhaps in Pre-Cambrian?
As a start, check out BBC clip of Deep Down & Dirty. This starts to bring the soil to life, which is seen mainly as 'worms and fungi'. Yet there is so much more in the soil food web, particularly the little arthropods. The 'meso' fauna are much smaller than worms, but visible only as specks. In terms of total biomass in the soil, mesofauna are much less than worms, in terms of numbers much more, and in terms of moving carbon around much the same - see CEH research. There are probably 500-1000 individual mesofauna for one worm, and the way they interact still needs to be explored.
These soil inhabitants give a clue to a possible answer that question about soil origins. The main families of organisms are remarkably consistent throughout the world. Does that help us determine the date?
Possible answer to the birth of the earth....
Possible answer to the birth of the earth....
When did our soil evolve?
Many people might think that an odd question. We don’t hear many people discussing when and how the body called ‘soil’ evolved. Yet it must have. If the soil is ‘living’ then it must have evolved alongside all of the other organisms. Yet it fails to get a mention. It is as if it has always been just there. Under our feet. But it hasn’t. The first life was probably in water or sediment, which is a long way from the composite, friable, clod of life we know today as ‘soil’. Yet, we would not be where we are today without it. We talk about the evolution of plants and animals, but rarely hear about the evolution of soil. Yet it is the same the world over – which tells us something.
We refer to the soil as ‘the living soil’, made famous by the self titled book by Lady Eve Balfour. We keep forgetting it is alive and a whole complicated ecosystem exists of countless relations not just between the fungi and worms, a popular perception. All the 100s of species mesofauna – small but quite minute creatures consisting mainly of mites, springtails, nematodes, live alongside the massive earthworms. There are many species, eating spores, roots, other creatures and providing the massive surface areas for the microflora to work on.
The vital part of the soil – which literally binds the world together, is only about an inch thick. It should not be seen as just a receptacle for chemical inputs. Soil is not just a physical or chemical entity but a biological ecosystem. An ecosystem that is capable of transforming rock into complex organisms within 50-100,000 years. There have been places and times when the fragile structures have broken down leading to dust bowls. Without it, quite simply, we along with many other creatures, are dead. Plants tend to be seen as an addition to the soil, yet it looks more likely that they developed relationships with soil animals - springtails and mites, integral to the evolution of soil.
These animals are not just an after-thought thrown in after the usual physical explanation for the development of soils where plants and later animals are thrown into the equation with no real analysis of how those biological entities transform the physical and chemical organisation. What is their role? We make guesses based on the animal appearance eg we can make out that some mites are predators not herbivores, by the shape of their mandibles, but we don’t know what they eat. (ref new Odum publication). Darwin taught us about how earthworms munch and crunch their way through. We now need somebody to explain the role of all these other creatures in creating the fragile living soil structure, and how these co-evolved and now co-exist.
So if this is living – perhaps not an organism, but certainly something like gaia predicts, And talking of Gaia, the Gaia man – James Lovelock said (at Hay Festival) that the trouble with all the climate change models is that they are only physico-chemical, that the living components are not yet computed in. We need to add the ‘biological’ into those algorithms, and the soil biology will be the biggest input.
So when do you think the soil evolved/appeared?
Ahem. My theory, my theory is that soil evolved between 400-300 million years ago (mya) and was in three phases - 50 million years covering the surface of the planet, and 50 million years composting, in between being a short spell of rapid development as roots went deeper. This can be backed up by three surrounding signals...1 Soil mesofauna & insects, 2 Physical-Chemical, and 3 Plants..
All this material was already produced when I was asked by somebody whether volcanic ash dust was involved, because there was a lot of it around the same time 375-350 mya. And here is the story that unfurled, about Essential Elements and the Evolution of Higher Plants and firming up many of the previous 'theory'. Now there is a mechanism.
As the two continents collided to make one, there was much volcanic activity and the resulting ash gave a perfect substrate for creatures to come on to the land from out of the sea and develop higher forms of plants and the soil itself. And the role of soil animals was probably crucial in stopping all the volcanic ash and plant debris just going into the oceans; instead the essential elements were recycled. In the soil..
So while it is a curious way to look at the history of the world - from the perspective of soil animals, it does allow us to bring in several other different sciences, and enables us to look at the whole better, and the movement and mechanisms of change become clearer.
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