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500 - 400mya
500 - 400mya
There was no soil half a billion (500mya) years ago, although we have seen in the previous 500 million years, metazoan creatures. However, the first signs of soil may have been emerging during these next 100 million years developed via biofilm.
Wet
Wet
We tend to describe the creation of life on land as 'conquering the dry conditions'. This is true. But It may well be better to consider the 'extension of wet conditions' too. This would be via thin water films - biofilms. There would be wierd water tensions, and those that can cope with that can go further inland. It is these biofilms that holds the rest together. Bacteria would be in them as well as tiny nematode worms. The biofilm thus becomes an environment of its own, somewhere other organisms could live. The more water the better it does that. After the average composition of living organisms is 65-90% water!
Healthy soil today is about 1/4 air and 1/4 water…but we have a long way to get there.
Dry
Dry
The big development over these 100 million years were the number of plants and creatures that could survive both wet and dry; this combination is essential for characters to live in soil. There are often long dry periods between the wet ones, so particular mechanisms have to be in place.
In particular, mosses which grow in moist conditions can withstand long periods of drought too. They increasingly covered much of the Earth, and housed the key characters, thereby creating the conditions for soil formation. We'll explore the next great soil development in the next phase.
Protozoans are the first visible organisms to emerge from their cysts, the protective cases they produced when the moss dried out. Twenty minutes later, the single cells have been joined by some tiny animals that have come out of dormancy. We can also find there rotifers, the smallest members of the animal kingdom. The little beasts appear to have two sets of rotating wheels—an illusion produced by tufts of cilia that beat in a wave - which gives these animals their name, Rotifers.
Biofilms for billion years
Biofilms for billion years
A biofilm is a community of microorganisms that attach to each other and to a surface, and are embedded in a slimy matrix Biofilms will carry bacteria and algae to live on land., but not widespread. Grow into lycopods. Biofilms full of bacteria were spreading across the plains, where lichens and fungi were starting to grow but not widespread
There were no lumps of ‘earth’. There are still no soils to be found. This means that for the first four billion years of this planet’s life there was no soil. Not a ped anywhere. There were not even the characters or conditions needed to make soil, hat give this planet’s name – Earth. However, there were early signs of some of the soil's processes and key components. which continued to emerge over the next hundred millions of years..Half a billion years ago there was nothing that looked like soil does today. But over theset 100 my we can find mosses, fungi, and bacteria that started creating debris. Key characters were arriving to make use of that.
We have seen the presence of various microbes, and the arrival of several plants and animals, some of which are going to make an impact on soil formation. Several key soil functions appeared and grew during the 100 million years from 500- 400mya. Perhaps the most significant was their ability to live in moist conditions but capable of withstanding dry periods.
Wet
Wet
We tend to describe the creation of life on land as 'conquering the dry conditions'. This is true. But It may well be better to consider the 'extension of wet conditions' too. This would be via thin water films - biofilms. There would be wierd water tensions, and those that can cope with that can go further inland. It is these biofilms that holds the rest together. Bacteria would be in them as well as tiny nematode worms. The biofilm thus becomes an environment of its own, somewhere other organisms could live. The more water the better it does that. After the average composition of living organisms is 65-90% water!
Healthy soil today is about 1/4 air and 1/4 water…but we have a long way to get there.
The extent and survival of mosses by around 400mya play a crucial part in soil evolution. They die leaving behind organic matter, which provides food for microbes and create the conditions for a host of small animals to live in stable conditions. Some of the inhabitants (like tardigrades and rotifers) may have existed much the same in the same environment since that time. Others, like nematodes and small creatures provide a mixture of undigested organic matter and metabolic waste products., that are recycled as nutrients. Small soil animal poo plays a vital role in soil formation. But there was no real soil structure.
Many creatures ran around then. The springtails could have sprung along the biofilms to find their food - bacteria, by following the raindrops and the smell of the earth, produced by those bacteria, that we know today. They developed mechanisms to jump along the films, but also be able to jump back to safety. This was a massive evolutionary advantage and a great leap for life.
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