Deep, Down and Dirty: The Science of Soil Page #2

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and twigs, it produces a rich

substance we call humus that becomes

part of the soil itself.

But the fungus is doing another

crucial job.

It's feeding an entire world

most of us don't even know exists.

Using specialist microphotography,

we can catch a rare glimpse

of an astonishing hidden kingdom...

..teeming with weird,

almost alien-looking life.

Millions of tiny creatures,

all of which are dependent

on nutrients being

released by the fungi.

These are nematodes,

tiny, round worms.

Scientists think there may be up

to half a million

species of these

wriggling in the soil.

There are mites, tiny

relatives of spiders and scorpions.

Tardigrades, often called 'water

bears' due to their cute appearance.

And rotifers, fascinating little

creatures that can propel themselves

through the soil using special hairs

that appear to revolve like a wheel.

This is the first great

secret of the soil. A vast,

living kingdom of tiny animals.

As they move around, eat

and are in turn eaten themselves,

they spread the essential nutrients

released by the fungi.

Helping to make the soil a more

fertile place for growing plants.

'Yet so far

we've only seen how fungi

'begin the process of unlocking

those nutrients.

'Breaking down all the tough remains

of dead plants is too large

'a job for fungi alone.

'But they have a secret ally

underground.

'An animal whose impact on the soil

is greater than any other.'

When it comes to ecosystems,

not all organisms are created equal.

By that, what I mean is the work

of one or two species will allow

hundreds of others to thrive.

One such animal is so important it's

been called an ecosystem engineer.

In this field, there might well be

over two million of them.

There are no prizes for guessing

which animal I'm seeking out here.

It's one that's inspired

generations of horticulturists

and agriculturists.

It is possibly the greatest

gardener on earth.

And it's this, the humble earthworm.

As a gardener,

I've long known that worms play

an important role in soil.

The great Charles Darwin devoted

over 40 years of study

to them, culminating in the

publication of his seminal work,

The Formation Of Vegetable Mould

Through The Actions Of Worms

With Observations On Their Habits.

You may not have heard of it,

but it sold faster

than On The Origin Of Species.

Darwin's studies, lesser known

than his work on evolution,

revealed an organism that was

essential for the life of the soil.

He became obsessed by them.

He fed them different diets,

tested their intelligence

and even tested their senses

by playing a bassoon to them.

What is about the earthworms

that beguiled Darwin?

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