0:00:06 > 0:00:09'Every spring, our planet is transformed.'
0:00:12 > 0:00:15A riot of new life bursting from the ground.
0:00:18 > 0:00:23'And it's all made possible by one rather misunderstood material.'
0:00:26 > 0:00:29From early childhood we're told that this stuff, dirt,
0:00:29 > 0:00:31is best avoided.
0:00:31 > 0:00:34But as someone with a lifelong passion for soil and
0:00:34 > 0:00:37everything that grows in it, it's a rule I've always enjoyed breaking.
0:00:41 > 0:00:46'I'm Chris Beardshaw. I spend my life designing and planting gardens.
0:00:47 > 0:00:50'Everything I do depends on soil.
0:00:52 > 0:00:57'And I'm going to try and convince you that it's an unrecognised
0:00:57 > 0:00:59'wonder of the natural world.'
0:01:02 > 0:01:04For billions of years
0:01:04 > 0:01:08our land must've looked pretty much like this.
0:01:08 > 0:01:14Bare rock. A barren place. Apparently devoid of life.
0:01:17 > 0:01:21But something transformed it into a vibrant, living planet.
0:01:24 > 0:01:27'And that something was soil.'
0:01:28 > 0:01:32But what fascinates me is where did the soil come from?
0:01:32 > 0:01:37What is it composed of and why is it so essential to life?
0:01:40 > 0:01:43So I'm going to get down and dirty with soil.
0:01:45 > 0:01:47I want to investigate its secrets.
0:01:49 > 0:01:54And reveal it as you've never seen it before. An intricate
0:01:54 > 0:01:56microscopic landscape...
0:01:59 > 0:02:02..teeming with strange and wonderful life forms.
0:02:04 > 0:02:07I'm going to reveal a world more complex
0:02:07 > 0:02:11and fragile than anything that exists above ground.
0:02:12 > 0:02:14A substance so remarkable,
0:02:14 > 0:02:18you'll never walk on the grass in the same way again.
0:02:38 > 0:02:41'As a gardener, I spend my life among plants.
0:02:41 > 0:02:44'I see them emerge from the soil.
0:02:44 > 0:02:48'But I've never really had the chance to discover what gives
0:02:48 > 0:02:51'soil its amazing, life-giving force.
0:02:58 > 0:03:00'So now I want to find out.
0:03:00 > 0:03:03'And I'm starting by doing what comes naturally.
0:03:04 > 0:03:06'I'm going out to dig.'
0:03:09 > 0:03:13Ask any gardener and they'll tell you that the soil
0:03:13 > 0:03:17provides their plants with the nutrients that are needed for life.
0:03:19 > 0:03:22And if you grow anything intensively,
0:03:22 > 0:03:25on farms or gardens, you have to apply fertiliser
0:03:25 > 0:03:29to replace and replenish those nutrients in the soil.
0:03:29 > 0:03:33In a natural landscape like this, all of these trees are being
0:03:33 > 0:03:37supported by the nutrients that are just inherently in the ground.
0:03:41 > 0:03:45But we shouldn't take these nutrients for granted.
0:03:45 > 0:03:49Like our fertilisers, they also need to be replenished.
0:03:50 > 0:03:54And how that happens is the first great mystery of soil.
0:03:57 > 0:04:00Even at the end of winter
0:04:00 > 0:04:03there's plenty of evidence of life on the woodland floor, or at least
0:04:03 > 0:04:05last season's life.
0:04:05 > 0:04:09Leaf litter, coming from the canopy above.
0:04:09 > 0:04:11But this is of no use at all to the surrounding plants
0:04:11 > 0:04:13in its current state.
0:04:19 > 0:04:24That's because most plants simply can't feed on dead leaves and twigs.
0:04:24 > 0:04:28They're too tough to break down and digest.
0:04:28 > 0:04:30And this creates a problem.
0:04:30 > 0:04:32Any nutrients they hold are locked in
0:04:32 > 0:04:34so the plants can't get at them.
0:04:35 > 0:04:38'But hidden beneath the surface of the soil
0:04:38 > 0:04:40'is a very different picture.'
0:04:43 > 0:04:48This modified-looking spade is actually a scientific instrument.
0:04:51 > 0:04:53The soil corer gives us
0:04:53 > 0:04:58the perfect cross section through the layers of the topsoil.
0:04:58 > 0:05:03At the top we can see here this unrotted layer of leaf litter.
0:05:03 > 0:05:07It's last season's leaves just sitting on the surface.
0:05:07 > 0:05:11But below that is a much darker layer where the
0:05:11 > 0:05:16particles are much more broken down, much smaller and quite compact.
0:05:16 > 0:05:20Beneath that is what we would recognise as topsoil.
0:05:20 > 0:05:24These are described by soil scientists as different horizons.
0:05:25 > 0:05:29'Collectively, the horizons are known as a soil profile.'
0:05:31 > 0:05:34And the deeper down the profile we go, the smaller
0:05:34 > 0:05:38the pieces of leaf and twig become until they just disappear.
0:05:39 > 0:05:43So somehow the tough plant matter is eventually broken down,
0:05:43 > 0:05:47releasing its trapped nutrients into the soil.
0:05:49 > 0:05:53This is one of the most vital processes in nature.
0:05:56 > 0:05:59'And it's begun by a rather unlikely hero.
0:06:00 > 0:06:01'To help track it down,
0:06:01 > 0:06:05'I'm joined by Lynne Boddy, Professor of Mycology
0:06:05 > 0:06:06'at Cardiff University.
0:06:10 > 0:06:13'We're on the hunt for an organism that prefers to stay
0:06:13 > 0:06:15'out of the light.'
0:06:15 > 0:06:17This is a likely-looking candidate, plenty of moss on the surface.
0:06:17 > 0:06:21Let's turn it over gently and see what we can see.
0:06:21 > 0:06:24- Look at that. - Oh, it's wonderful, isn't it?
0:06:24 > 0:06:28Absolutely covered, it's almost like a spider's web under here, isn't it?
0:06:28 > 0:06:30It is. This is fungus.
0:06:31 > 0:06:35The crucial thing about the fungi is that they release nutrients
0:06:35 > 0:06:38which allow plants to continue to grow.
0:06:38 > 0:06:41The main body of the fungus is called the mycelium, which is
0:06:41 > 0:06:43made up of very, very, very fine filaments,
0:06:43 > 0:06:47they're too small to see by the naked eye. But here they're aggregated
0:06:47 > 0:06:53together to form cord- or root-like structures that we can clearly see.
0:06:53 > 0:06:55What do these threads do?
0:06:55 > 0:06:59They grow out from this wood in search of new resources,
0:06:59 > 0:07:04so maybe the resources would be dead leaves, more wood.
0:07:04 > 0:07:09When they find them they exude enzymes that break down the structure
0:07:09 > 0:07:14of the wood or the leaves or any other bits of dead plant material.
0:07:19 > 0:07:21It's easy to overlook fungi.
0:07:23 > 0:07:24But, to me,
0:07:24 > 0:07:27they're true champions of the natural world.
0:07:29 > 0:07:32They begin the process of breaking down dead wood
0:07:32 > 0:07:36and leaves to release the nutrients trapped inside.
0:07:38 > 0:07:40It's an extremely rare ability.
0:07:44 > 0:07:47The thing about the wood decay fungi is that actually
0:07:47 > 0:07:51they are the only organism or almost the only organism that can
0:07:51 > 0:07:55actually break down wood on this planet, and that is one
0:07:55 > 0:07:58of the reasons why they're so important, because otherwise
0:07:58 > 0:08:03we'd be up to our armpits in dead stuff. And, in fact, plants
0:08:03 > 0:08:06wouldn't be able to grow because all the nutrients
0:08:06 > 0:08:09on this planet would be locked up in the dead plant material.
0:08:11 > 0:08:16As the fungus breaks down the leaves and twigs, it produces a rich
0:08:16 > 0:08:21substance we call humus that becomes part of the soil itself.
0:08:23 > 0:08:26But the fungus is doing another crucial job.
0:08:27 > 0:08:32It's feeding an entire world most of us don't even know exists.
0:08:38 > 0:08:41Using specialist microphotography,
0:08:41 > 0:08:45we can catch a rare glimpse of an astonishing hidden kingdom...
0:08:48 > 0:08:52..teeming with weird, almost alien-looking life.
0:08:55 > 0:08:59Millions of tiny creatures, all of which are dependent
0:08:59 > 0:09:01on nutrients being released by the fungi.
0:09:05 > 0:09:08These are nematodes, tiny, round worms.
0:09:10 > 0:09:14Scientists think there may be up to half a million
0:09:14 > 0:09:17species of these wriggling in the soil.
0:09:24 > 0:09:28There are mites, tiny relatives of spiders and scorpions.
0:09:35 > 0:09:40Tardigrades, often called 'water bears' due to their cute appearance.
0:09:47 > 0:09:52And rotifers, fascinating little creatures that can propel themselves
0:09:52 > 0:09:57through the soil using special hairs that appear to revolve like a wheel.
0:10:07 > 0:10:11This is the first great secret of the soil. A vast,
0:10:11 > 0:10:14living kingdom of tiny animals.
0:10:19 > 0:10:23As they move around, eat and are in turn eaten themselves,
0:10:23 > 0:10:26they spread the essential nutrients released by the fungi.
0:10:30 > 0:10:35Helping to make the soil a more fertile place for growing plants.
0:10:46 > 0:10:49'Yet so far we've only seen how fungi
0:10:49 > 0:10:52'begin the process of unlocking those nutrients.
0:10:54 > 0:10:58'Breaking down all the tough remains of dead plants is too large
0:10:58 > 0:11:00'a job for fungi alone.
0:11:02 > 0:11:04'But they have a secret ally underground.
0:11:06 > 0:11:11'An animal whose impact on the soil is greater than any other.'
0:11:13 > 0:11:17When it comes to ecosystems, not all organisms are created equal.
0:11:18 > 0:11:23By that, what I mean is the work of one or two species will allow
0:11:23 > 0:11:25hundreds of others to thrive.
0:11:28 > 0:11:34One such animal is so important it's been called an ecosystem engineer.
0:11:36 > 0:11:41In this field, there might well be over two million of them.
0:11:44 > 0:11:48There are no prizes for guessing which animal I'm seeking out here.
0:11:50 > 0:11:53It's one that's inspired generations of horticulturists
0:11:53 > 0:11:55and agriculturists.
0:11:55 > 0:11:58It is possibly the greatest gardener on earth.
0:12:00 > 0:12:03And it's this, the humble earthworm.
0:12:06 > 0:12:08As a gardener,
0:12:08 > 0:12:11I've long known that worms play an important role in soil.
0:12:13 > 0:12:17The great Charles Darwin devoted over 40 years of study
0:12:17 > 0:12:22to them, culminating in the publication of his seminal work,
0:12:22 > 0:12:26The Formation Of Vegetable Mould Through The Actions Of Worms
0:12:26 > 0:12:29With Observations On Their Habits.
0:12:29 > 0:12:31You may not have heard of it,
0:12:31 > 0:12:35but it sold faster than On The Origin Of Species.
0:12:39 > 0:12:43Darwin's studies, lesser known than his work on evolution,
0:12:43 > 0:12:47revealed an organism that was essential for the life of the soil.
0:12:47 > 0:12:50He became obsessed by them.
0:12:50 > 0:12:53He fed them different diets, tested their intelligence
0:12:53 > 0:12:57and even tested their senses by playing a bassoon to them.
0:12:58 > 0:13:01What is about the earthworms that beguiled Darwin?
0:13:01 > 0:13:03Just why are they so important?
0:13:09 > 0:13:14Well, first of all the sheer scale of the worm operation.
0:13:14 > 0:13:18As they tunnel into the ground in their millions,
0:13:18 > 0:13:23their burrows permeate the earth like a vast ventilation system,
0:13:23 > 0:13:28providing essential supplies of air to everything else that
0:13:28 > 0:13:29lives in the soil.
0:13:35 > 0:13:38But that's not the earthworms' only talent.
0:13:38 > 0:13:41They also continue what the fungi began.
0:13:43 > 0:13:46They eat and digest dead leaves underground,
0:13:46 > 0:13:48unlocking their trapped nutrients.
0:13:50 > 0:13:53The way they do this reveals one of the most fundamental
0:13:53 > 0:13:55secrets of soil.
0:13:59 > 0:14:00But it's hard to see.
0:14:09 > 0:14:12'So I've come to meet Mark Hodson, Professor
0:14:12 > 0:14:15'of Environmental Science at York University.'
0:14:15 > 0:14:19I find they're very fun creatures, you see them a lot.
0:14:19 > 0:14:22If you walk around after the rain you see them crawling around.
0:14:22 > 0:14:27'He's spent years studying what and how worms eat.'
0:14:27 > 0:14:28They go up and down.
0:14:28 > 0:14:31During the day, they stay in the bottom of their burrows.
0:14:31 > 0:14:33At night they come out onto the surface, they look round,
0:14:33 > 0:14:36sort of, sometimes they keep their tails anchored in their burrows.
0:14:36 > 0:14:40They sort of stretch out and eat or grab organic material,
0:14:40 > 0:14:43they pull it down into their burrows to eat later on.
0:14:43 > 0:14:46And the undigested material gets squirted out of the back end and that
0:14:46 > 0:14:51helps make all of this black, browny stuff which is the soil.
0:14:54 > 0:14:58Nothing is quicker at breaking down dead leaves than an earthworm.
0:15:01 > 0:15:05It's thought that in the average field the worms get through
0:15:05 > 0:15:09a staggering one and a half tonnes of plant matter every year.
0:15:11 > 0:15:14They're like leaf-processing factories,
0:15:14 > 0:15:16operating on an industrial scale.
0:15:18 > 0:15:23Yet they look nothing more than a simple, fleshy tube.
0:15:23 > 0:15:25So what's going on inside?
0:15:27 > 0:15:32To help answer that, Mark has been doing a rather unsavoury experiment.
0:15:34 > 0:15:38This Petri dish contains a sample of plain soil.
0:15:38 > 0:15:42And this one was made using earth that has passed through
0:15:42 > 0:15:45an earthworm. In other words, worm poo.
0:15:47 > 0:15:50Mark's been comparing the two and he's uncovered
0:15:50 > 0:15:55evidence of a hidden army of secret agents at work within the worm.
0:15:57 > 0:15:58Bacteria.
0:16:00 > 0:16:03So each of these spots is a bacterial colony. You can see
0:16:03 > 0:16:05there are far more growing here
0:16:05 > 0:16:08from the material that's just come out of the earthworm gut.
0:16:08 > 0:16:12So the earthworm ingests the soil, there are bacteria in there already,
0:16:12 > 0:16:17and the earthworm gut environment is good for bacteria.
0:16:17 > 0:16:22It's moist, its got the right pH, the earthworm is secreting mucous
0:16:22 > 0:16:25full of polysaccharide sugars, which the bacteria love to eat.
0:16:26 > 0:16:28So it's bacteria
0:16:28 > 0:16:31that finish the job of breaking down dead plant matter.
0:16:35 > 0:16:38There are billions of them naturally present in the ground,
0:16:38 > 0:16:44like workers on a production line turning dead plants into new soil.
0:16:47 > 0:16:49But inside the earthworm
0:16:49 > 0:16:54this activity is magnified to levels that are truly mind-blowing.
0:16:57 > 0:17:00If you do counts on the soil in earthworm guts
0:17:00 > 0:17:04you can have 1,000 times more active bacteria in that soil
0:17:04 > 0:17:07than the bulk soil surrounding the earthworm.
0:17:07 > 0:17:10What it's proving is the earthworms have ramped up
0:17:10 > 0:17:13the bacterial activity in the soil.
0:17:17 > 0:17:20And it's this army of bacteria,
0:17:20 > 0:17:25hidden in the guts of earthworms, that completes the vital cycle.
0:17:27 > 0:17:30Unlocking all the nutrients from dead leaves
0:17:30 > 0:17:32and releasing them back into the soil.
0:17:35 > 0:17:41We very often think of soil as being brown, solid, inert stuff.
0:17:41 > 0:17:49But there's more life within in it than flies, swims or walks above it.
0:17:49 > 0:17:53And, far from being a haphazard array of organisms,
0:17:53 > 0:17:57this is a complex range of interconnected structures
0:17:57 > 0:18:00that support the life above.
0:18:08 > 0:18:13As we've seen, it takes a combination of plants, fungi,
0:18:13 > 0:18:18animals and bacteria all working together to keep nutrients
0:18:18 > 0:18:20flowing from the dead to the living.
0:18:22 > 0:18:27In the process, new soil is created which in turn supports
0:18:27 > 0:18:31even more life, making a cycle that keeps the soil fertile.
0:18:34 > 0:18:38Yet so far we've only scratched the surface of the soil.
0:18:39 > 0:18:43Everything we've seen happens within just the topmost layers.
0:18:53 > 0:18:57'Look deeper and there's far more to soil than this.
0:19:00 > 0:19:04'To reveal just how much, I first need a bit of heat.'
0:19:15 > 0:19:19What I have here is dried topsoil.
0:19:19 > 0:19:21I want to find out how much of this is
0:19:21 > 0:19:25derived from plants by setting fire to it.
0:19:25 > 0:19:28If it's 100% plant material, there should be nothing left.
0:19:30 > 0:19:33So I'm starting with 100g.
0:19:33 > 0:19:36'Let's see how much remains.'
0:19:48 > 0:19:52As this is burning away, the soil is completely transforming colour.
0:19:52 > 0:19:57It's going from a soft brown to almost a carbon colour.
0:19:57 > 0:20:00Very similar to the embers in a barbecue.
0:20:01 > 0:20:05The soil particles are fracturing, breaking apart. The organic matter
0:20:05 > 0:20:08binding them together is burning away and the soil particles are
0:20:08 > 0:20:10just falling to pieces.
0:20:13 > 0:20:17'The plant matter is turning into gases like carbon dioxide
0:20:17 > 0:20:19'that are lost into the air.
0:20:22 > 0:20:27'After about 15 minutes of intense heat, I'm going to weigh it again.'
0:20:29 > 0:20:31See how much we've lost? We started off with about 100,
0:20:31 > 0:20:33it's now down to 70.
0:20:33 > 0:20:37So about 30% of this original soil was plant based.
0:20:37 > 0:20:39It's burnt away.
0:20:39 > 0:20:42Clearly, there's more to soil than just plant material.
0:20:48 > 0:20:53To see what that is, we need to get beneath the topsoil
0:20:53 > 0:20:54and look deeper down.
0:20:57 > 0:21:01'This is Scolly's Cross in Aberdeenshire, where
0:21:01 > 0:21:05'a landslide has exposed the layers of soil beneath the pine forest.
0:21:08 > 0:21:10'It's something we rarely get to see,
0:21:10 > 0:21:13'as all this is usually hidden underground.'
0:21:19 > 0:21:24In a landslip situation like this we get to examine perfectly
0:21:24 > 0:21:30the soil profile, the horizons or layers of various materials.
0:21:30 > 0:21:33At the top we've got the vegetation
0:21:33 > 0:21:37and, below, the various layers or horizons of soil,
0:21:37 > 0:21:42each with a different characteristic in terms of colours and textures.
0:21:42 > 0:21:45The topsoils, going down into the subsoils with the roots
0:21:45 > 0:21:47penetrating, this is what we saw in the forest.
0:21:52 > 0:21:58But, as we go further down, the dark organic plant material disappears.
0:21:58 > 0:22:00We seem to have left the soil behind.
0:22:04 > 0:22:06These deeper layers are mainly
0:22:06 > 0:22:09made up of fragments of the underlying rock.
0:22:11 > 0:22:13And then further down we're into bedrock.
0:22:15 > 0:22:21Collectively, these layers form the foundation of soil development.
0:22:29 > 0:22:31Rock fragments permeate the soil
0:22:31 > 0:22:34from the bedrock all the way to the surface.
0:22:37 > 0:22:39It's mainly this stuff that was left behind
0:22:39 > 0:22:43when I burned the plant matter away from the topsoil.
0:22:48 > 0:22:51But, though these particles are from lifeless rock,
0:22:51 > 0:22:54that doesn't mean they have no purpose.
0:22:56 > 0:23:01In fact, they are fundamental to how soil works.
0:23:10 > 0:23:14Soil particles are divided into three different categories
0:23:14 > 0:23:18depending on the size of the particle.
0:23:18 > 0:23:21The largest being sand. There you can see them
0:23:21 > 0:23:25just coming into focus, wonderful, rounded particles.
0:23:25 > 0:23:29The next size down, well, it's silt.
0:23:31 > 0:23:35And there you can start to see the individual silt particles.
0:23:36 > 0:23:39And the very smallest are the clays.
0:23:41 > 0:23:45Search for the clay. There they are, much smaller.
0:23:46 > 0:23:51Relatively speaking, if the sand was the size of a beach ball
0:23:51 > 0:23:55then the clay particles would be the size of a pin head.
0:23:55 > 0:23:59Incredibly small and flat in their profile.
0:24:00 > 0:24:04What's curious about the particles is that the relative
0:24:04 > 0:24:08proportions of them in any soil fundamentally affect
0:24:08 > 0:24:13how that soil behaves, and, more importantly, how it supports life.
0:24:24 > 0:24:28'To see exactly how, I've come to the James Hutton Institute
0:24:28 > 0:24:29'in Aberdeen.
0:24:32 > 0:24:36'I'm here to meet soil scientist Dr Jason Owen.'
0:24:38 > 0:24:41Jason, what will this experiment demonstrate?
0:24:41 > 0:24:44What we have here are three cylinders. One with a sand, one
0:24:44 > 0:24:48with a silt-dominated soil and one with a clayed soil.
0:24:48 > 0:24:51When we pour water in the top what we'll see is the water
0:24:51 > 0:24:54percolating through the soil profile.
0:24:54 > 0:24:56With the sand it'll go very quickly.
0:25:00 > 0:25:02With a clay it'll go very slowly.
0:25:06 > 0:25:08And the silt will be somewhere in between.
0:25:10 > 0:25:15To me, this is familiar stuff, as it will be to any gardener.
0:25:18 > 0:25:23It's the age-old question of drainage. How well water
0:25:23 > 0:25:25moves through different types of soil.
0:25:27 > 0:25:28With the sand, large particles,
0:25:28 > 0:25:31there's quite large gaps, comparatively speaking,
0:25:31 > 0:25:34and water can go down through the profile.
0:25:34 > 0:25:39With the clay, very small particles, and as a result the gaps
0:25:39 > 0:25:42where water can penetrate are exceptionally small.
0:25:44 > 0:25:47The silt is somewhere in between the two extremes.
0:25:48 > 0:25:51But to really see what's going on inside the soil
0:25:51 > 0:25:54we have to look at it in far greater detail.
0:25:55 > 0:25:59Here, they're using cutting edge technology to examine soil
0:25:59 > 0:26:01on an incredibly small scale.
0:26:04 > 0:26:06We're joined by Evelyne Delbos,
0:26:06 > 0:26:11operator of the Scanning Electron Microscope at the Hutton Institute.
0:26:12 > 0:26:16She's looking at soil magnified 400 times.
0:26:18 > 0:26:21I have the three main parts of the soil.
0:26:21 > 0:26:24The sand grains here.
0:26:24 > 0:26:28On the right is the silt and the clay at the bottom.
0:26:28 > 0:26:31Well, you can sort of see with the clay, for example,
0:26:31 > 0:26:34it's stacked so tightly together
0:26:34 > 0:26:38that you can actually not see discernible gaps between them.
0:26:38 > 0:26:42Whereas here we've got these very large sand particles
0:26:42 > 0:26:44and even through they're right on top of each other
0:26:44 > 0:26:46you can still see the far larger gaps.
0:26:46 > 0:26:50That allows air, for aeration of the soil,
0:26:50 > 0:26:53and it also allows water movement through the soil.
0:26:55 > 0:26:58But there's more going on here than just how the particles
0:26:58 > 0:27:00are packed together.
0:27:00 > 0:27:03Let's imagine this is a grain of sand.
0:27:03 > 0:27:07And the surface area of that grain of sand is that surface,
0:27:07 > 0:27:10that surface, that surface, and that's it.
0:27:10 > 0:27:16It we take, by comparison, the same volume of clay
0:27:16 > 0:27:21then you have that surface plus that surface plus that surface, so you
0:27:21 > 0:27:26can imagine already that the surface area is much, much, much larger.
0:27:26 > 0:27:30So what does the surface area do to the water?
0:27:30 > 0:27:32What's the relationship between those two things?
0:27:32 > 0:27:37What's interesting about many clays, it has an electric charge
0:27:37 > 0:27:40associated with its surfaces.
0:27:40 > 0:27:45Many nutrients that are dissolved within the water can be
0:27:45 > 0:27:50attracted to these clay sites, to this large surface area,
0:27:50 > 0:27:51and then held,
0:27:51 > 0:27:55basically for root systems then to uptake for plant growth.
0:27:55 > 0:28:01So clay particles have an electrical charge that can bind nutrients
0:28:01 > 0:28:02and water to them.
0:28:04 > 0:28:08This allows soil to act as both larder
0:28:08 > 0:28:11and reservoir for plants and animals.
0:28:11 > 0:28:15Sounds ideal, but there's a catch.
0:28:15 > 0:28:19Too much clay and the soil can act like a sponge
0:28:19 > 0:28:21and can quickly become waterlogged.
0:28:22 > 0:28:25At the other end of the scale, too much sand
0:28:25 > 0:28:28and the water can run through too quickly,
0:28:28 > 0:28:32washing the nutrients out and leaving behind soil that's dry.
0:28:40 > 0:28:43Have we got an image of what a good soil should look like?
0:28:45 > 0:28:50Here you can see some grains of sand, they are different sizes.
0:28:50 > 0:28:54It's a mixture and you can also have there and there the clay
0:28:54 > 0:28:57and the silt all mixed up.
0:28:57 > 0:29:01So this is demonstrating the ideal, in terms of soil. It would
0:29:01 > 0:29:04be free draining, retain sufficient moisture,
0:29:04 > 0:29:07sufficient nutrients, what about microbial activity?
0:29:07 > 0:29:11This is a very, very complicated 3D structure
0:29:11 > 0:29:14which gives all of the microbiota
0:29:14 > 0:29:20within the soil effectively a niche, a home to live, and as a result
0:29:20 > 0:29:25the ecosystems that exist in the soil are exceptionally complicated.
0:29:25 > 0:29:27This is a classic example where you've got the mix between the
0:29:27 > 0:29:31large particles, the clay particles and silt all working together.
0:29:37 > 0:29:43So the elements that make up soil come from two very different places.
0:29:43 > 0:29:47The chaos of life, and the inert world of rock.
0:29:49 > 0:29:54Together, they create an intricate substance that can naturally
0:29:54 > 0:29:58feed and water all plant life on earth.
0:30:00 > 0:30:04And it makes me wonder just how did this strange
0:30:04 > 0:30:07alliance between rock and life begin?
0:30:11 > 0:30:16'How did the very first soil come to exist?'
0:30:23 > 0:30:26To find out, we need to go back to a time
0:30:26 > 0:30:31and place before the first soil appeared on the planet.
0:30:34 > 0:30:37That's not quite as difficult as it might sound.
0:30:40 > 0:30:45This is Malham Cove, an inland cliff deep in the Yorkshire Dales.
0:30:48 > 0:30:52It's a striking landscape, built from limestone
0:30:52 > 0:30:56and sculpted by the awesome power of ice.
0:31:04 > 0:31:08This place offers a wonderful window into the Earth
0:31:08 > 0:31:13billions of years ago, before there was soil.
0:31:13 > 0:31:16That's because at the end of the last Ice Age,
0:31:16 > 0:31:20as temperatures rose and the ice retreated, it left this
0:31:20 > 0:31:24naked rock. Any soil that had been here had been scoured away
0:31:24 > 0:31:27and deposited somewhere in that direction.
0:31:27 > 0:31:32And as a consequence any soil you see here is relatively new,
0:31:32 > 0:31:34in fact, it's still forming.
0:31:34 > 0:31:37Making this one of the best places in the country to discover
0:31:37 > 0:31:42how we get from this naked rock, to this. Soil that supports life.
0:31:46 > 0:31:51I'm joined by Professor Steven Nortcliff from Reading University.
0:31:51 > 0:31:53Landscape is fascinating in terms of the soil.
0:31:55 > 0:31:59First, I want to know what could possibly start to break up
0:31:59 > 0:32:02something as seemingly permanent as rock.
0:32:04 > 0:32:06We've got to break it down.
0:32:06 > 0:32:09And we've got evidence here in this landscape
0:32:09 > 0:32:12of those early stages of breakdown.
0:32:12 > 0:32:18We have ice forming in the fissures in the rock and as the ice expands
0:32:18 > 0:32:22it forces the rock apart. And that's the first form of disintegration.
0:32:23 > 0:32:26When water freezes, it expands.
0:32:27 > 0:32:30If that expansion happens within a crack,
0:32:30 > 0:32:35it can exert a force strong enough to break rock apart.
0:32:40 > 0:32:42And you can witness this in your own freezer at home.
0:32:42 > 0:32:46You fill the ice tray and when it freezes there's expansion.
0:32:46 > 0:32:49But it seems remarkable that that expansion is powerful enough
0:32:49 > 0:32:50to blow rock apart.
0:32:50 > 0:32:53Well, you're expanding in a confined space.
0:32:53 > 0:32:56It only has one way to expand and that's sideways.
0:32:56 > 0:33:00That forces the rock apart and it's the beginning
0:33:00 > 0:33:03of the disintegration to give us the soil.
0:33:13 > 0:33:15This process is called physical weathering.
0:33:16 > 0:33:19It breaks down rock by sheer brute force.
0:33:21 > 0:33:24But we're still a long way from soil.
0:33:26 > 0:33:29Next comes a different process entirely.
0:33:31 > 0:33:33And it starts with rain.
0:33:37 > 0:33:40We'll just drop some hydrochloric acid onto limestone.
0:33:42 > 0:33:43You can see it fizzing.
0:33:43 > 0:33:48You can hear it fizzing. It's really going at it.
0:33:50 > 0:33:51What Stephen's showing me
0:33:51 > 0:33:56is an exaggerated version of what happens every time it rains.
0:33:56 > 0:34:01Rain is slightly acidic and, with limestone,
0:34:01 > 0:34:07when this slightly acidic water falls on the surface it weathers it.
0:34:08 > 0:34:11And is that what we're seeing here, on the surface of the rock?
0:34:11 > 0:34:13That is exactly what we're seeing here.
0:34:20 > 0:34:26So rain reacts with the rock, gradually dissolving it. This is
0:34:26 > 0:34:31chemical weathering. The second key step towards soil.
0:34:35 > 0:34:38Using a stronger acid to speed the process up,
0:34:38 > 0:34:42we can see just how powerful it is.
0:34:43 > 0:34:48Here, a piece of rock is almost entirely dissolved. Leaving
0:34:48 > 0:34:53behind nothing but insoluble, sandy remains known as sediments.
0:34:55 > 0:34:58And that's the beginning of the soil.
0:34:58 > 0:35:00It's a very small amount of insoluble residue,
0:35:00 > 0:35:03but that's where the soil development starts.
0:35:10 > 0:35:17But sediment isn't yet soil. There's something fundamental missing.
0:35:19 > 0:35:24Life. But look closely, and this rock is not bare.
0:35:26 > 0:35:29It's covered in this, lichen.
0:35:30 > 0:35:34And this is what causes the final,
0:35:34 > 0:35:41almost magical metamorphosis from inert rock, to life-giving soil.
0:35:42 > 0:35:44In this environment they are key
0:35:44 > 0:35:49because the lichen will attack the rock, very much like the chemical
0:35:49 > 0:35:53weathering we saw, but it will break it down, release nutrients.
0:35:56 > 0:36:01Lichen is actually two organisms, algae and fungus,
0:36:01 > 0:36:03living in one body.
0:36:06 > 0:36:10And though it seems almost incredible, the fungus part is able
0:36:10 > 0:36:16to break down the rock to release nutrients that it can feed on.
0:36:16 > 0:36:19Much as we saw the fungi do with the wood in the forest.
0:36:22 > 0:36:27Over time, generations of lichen grow over one another,
0:36:27 > 0:36:29the new on top of the dead.
0:36:30 > 0:36:32The dead remains form organic matter.
0:36:35 > 0:36:40And when this mixes with sediment the result is soil.
0:36:43 > 0:36:47And so from an apparently barren limestone pavement up here
0:36:47 > 0:36:52we have the complete story of the generation of our soils.
0:36:52 > 0:36:57Bare rock through the various weathering processes, the biological
0:36:57 > 0:37:01processes and eventually the formation of soil. It is all here.
0:37:01 > 0:37:03Condensed into just a few square metres.
0:37:03 > 0:37:08Yeah, it's a wonderful example of soil development in motion.
0:37:08 > 0:37:13And what we've got is different areas representing different timescales -
0:37:13 > 0:37:15some it's just starting,
0:37:15 > 0:37:17others it's been going on for a few thousand years.
0:37:30 > 0:37:35Soil is the place where the relatively inert world of rock meets
0:37:35 > 0:37:38the riot of life above.
0:37:38 > 0:37:42It's a complex, staggeringly complex ecosystem,
0:37:42 > 0:37:46but it also offers something of a conundrum
0:37:46 > 0:37:48because the life creates soil,
0:37:48 > 0:37:52breaking down organic matter and
0:37:52 > 0:37:58forcing rocks apart, but that life is also dependent upon the soil
0:37:58 > 0:38:03for nutrients, moisture, habitat, anchorage, somewhere to live.
0:38:05 > 0:38:10That means there's a delicate balance between the life and the soil.
0:38:11 > 0:38:13Challenge one and you inevitably challenge the other.
0:38:21 > 0:38:25And today that ancient balance between rock and life
0:38:25 > 0:38:29is being challenged as never before in history.
0:38:31 > 0:38:37A new force has entered the world of the soil. Humankind.
0:38:43 > 0:38:45In geological terms,
0:38:45 > 0:38:51human civilisation is a mere blink of the eye, at around about
0:38:51 > 0:38:579,000 years. And in that brief moment in time we've arguably done
0:38:57 > 0:39:02more to change our soils than in the previous 400 million years.
0:39:08 > 0:39:09We've mined it.
0:39:11 > 0:39:13Built on it.
0:39:14 > 0:39:15Farmed on it.
0:39:18 > 0:39:21And, in places like this, drained it.
0:39:24 > 0:39:29And our actions have had consequences we never imagined.
0:39:33 > 0:39:37East Anglia is famed for its fenland landscape. One of rivers,
0:39:37 > 0:39:40marshes and streams.
0:39:40 > 0:39:44But what we have left is just a fraction of what was once here.
0:39:44 > 0:39:48Largely because this is a habitat that's prone to flooding
0:39:48 > 0:39:50and since the 17th century
0:39:50 > 0:39:55generation after generation have been progressively draining it.
0:39:55 > 0:40:00The great system of canals and ditches have been dug.
0:40:00 > 0:40:03To drain the unwanted water into the sea.
0:40:03 > 0:40:06Over the past 300 or so years,
0:40:06 > 0:40:09the population of the UK has grown rapidly.
0:40:11 > 0:40:15This put huge pressure on places like the fens.
0:40:16 > 0:40:21To help feed all those extra mouths, we needed to dry out
0:40:21 > 0:40:25the waterlogged land to make way for the business of agriculture.
0:40:27 > 0:40:30Rivers and lakes were drained and crops planted.
0:40:31 > 0:40:34The few people who lived there were thought rough and unfriendly.
0:40:36 > 0:40:39Old ways of life and traditional pastimes that had grown up
0:40:39 > 0:40:42around the flooding were swept aside.
0:40:43 > 0:40:46But this progress came with a sting in the tail.
0:40:49 > 0:40:52As the rivers and meres were drained,
0:40:52 > 0:40:54something unexpected happened.
0:40:54 > 0:40:56The land began to sink.
0:41:00 > 0:41:04This is Holm Fen, drained in the 1850s.
0:41:05 > 0:41:08It was the home of Whittlesea Mere,
0:41:08 > 0:41:11once thought to be the second largest lake in England.
0:41:12 > 0:41:14This is all that's left.
0:41:20 > 0:41:25Previous experience had demonstrated that if you drain the fens
0:41:25 > 0:41:27the land would sink.
0:41:27 > 0:41:30So a local landowner here at Holme Fen, William Wells,
0:41:30 > 0:41:33decided to measure that process.
0:41:33 > 0:41:35He took a post and pushed it into the ground
0:41:35 > 0:41:40until the top was completely covered. And that post today?
0:41:40 > 0:41:41Well, here it is.
0:41:43 > 0:41:46The top of the post was originally ground level.
0:41:46 > 0:41:49Since 1850 this whole tract of land
0:41:49 > 0:41:52has sunk somewhere in the region of four metres,
0:41:52 > 0:41:56making this one of the lowest places in Britain.
0:41:56 > 0:42:01There can surely be no clearer indication of the effect
0:42:01 > 0:42:04of human interference on soil.
0:42:04 > 0:42:07But why did it sink? And what are the consequences?
0:42:12 > 0:42:15'I'm joined by Dr Ian Homan.
0:42:15 > 0:42:16'He and his colleagues at
0:42:16 > 0:42:20'Cranfield University have extensively studied the area.
0:42:22 > 0:42:25'We're going to take a look at a rather special type of soil
0:42:25 > 0:42:27'found here in the fens.
0:42:30 > 0:42:32'This is peat.'
0:42:34 > 0:42:36- Pretty good profile.- It is indeed.
0:42:36 > 0:42:40Peat forms in a wetland environment, so the soils are waterlogged.
0:42:40 > 0:42:44It's low in oxygen under the surface and it's quite acidic.
0:42:44 > 0:42:46So the combination of the waterlogged nature,
0:42:46 > 0:42:52the lack of oxygen and acidity slows down the rate of decomposition.
0:42:52 > 0:42:56The soil bacteria and the microbiological
0:42:56 > 0:43:00components of the soil aren't able to decompose that organic material.
0:43:00 > 0:43:02So it accumulates very slowly.
0:43:07 > 0:43:12So in peat, instead of being broken down, plant material builds up.
0:43:15 > 0:43:17And this has an important effect.
0:43:20 > 0:43:24Plants grow using carbon dioxide from the air.
0:43:26 > 0:43:29And if they're not broken down when they die
0:43:29 > 0:43:33they and the carbon they contain become trapped within the soil.
0:43:35 > 0:43:38This is what's known as a carbon sink
0:43:38 > 0:43:41and peat bogs are some of the best.
0:43:43 > 0:43:47But remove the water, and the balance changes.
0:43:49 > 0:43:54Oxygen enters the soil, allowing bacteria and fungi to breathe.
0:43:56 > 0:43:59This is what happened when the fens were drained
0:43:59 > 0:44:02and it had profound consequences.
0:44:05 > 0:44:09That allows the micro-organisms to use the carbon within this peat
0:44:09 > 0:44:12as an energy source, converting
0:44:12 > 0:44:15the carbon into carbon dioxide and energy.
0:44:15 > 0:44:20The fens, we think, are losing about four million cubic metres of
0:44:20 > 0:44:25peat soil every year and that equates to an emission of carbon dioxide
0:44:25 > 0:44:29of about 1, 1½ million tonnes of carbon dioxide a year.
0:44:30 > 0:44:33We've gone from being an environment
0:44:33 > 0:44:36that should be storing carbon dioxide into the soil
0:44:36 > 0:44:41into an environment now that is emitting carbon dioxide.
0:44:41 > 0:44:44So the story of the fens really is that it's the worst possible,
0:44:44 > 0:44:46for both ends of the spectrum.
0:44:46 > 0:44:49Not only are we losing the carbon sink,
0:44:49 > 0:44:52- but the carbon dioxide is being released into the atmosphere. - Indeed.
0:44:59 > 0:45:03So as a result of human activity four metres of peat,
0:45:03 > 0:45:09which took thousands of years to form, disappeared in mere decades.
0:45:10 > 0:45:15And this old post is a monument to what can happen
0:45:15 > 0:45:18when we upset the balance within the soils.
0:45:25 > 0:45:29It's a story that's repeated throughout human history.
0:45:29 > 0:45:32Archaeological records very clearly demonstrate
0:45:32 > 0:45:38that, as our nomadic ancestors began to settle and farm the land,
0:45:38 > 0:45:41populations increased dramatically.
0:45:41 > 0:45:43And in order to feed the population
0:45:43 > 0:45:48the area of land that was turned over to the plough also increased.
0:45:50 > 0:45:54Those early farmers tilled and ploughed, fertilised
0:45:54 > 0:45:58and irrigated in the best way they knew how.
0:46:00 > 0:46:01But, as we've seen,
0:46:01 > 0:46:06human interference can have unexpected consequences.
0:46:10 > 0:46:14Ploughing and tilling can destroy the soil's structure.
0:46:14 > 0:46:19Intensive farming will deplete the soil of nutrients
0:46:19 > 0:46:23and over-irrigation can cause high levels of toxicity.
0:46:24 > 0:46:29When these factors combine the soil becomes degraded
0:46:29 > 0:46:32and prone to erosion from wind and water.
0:46:37 > 0:46:41For me, recent history provides a stark warning.
0:46:43 > 0:46:47By the 1930s, vast swathes of the North American prairies
0:46:47 > 0:46:50were turned over to the plough.
0:46:52 > 0:46:55All the way from Canada down to Texas.
0:46:57 > 0:47:00But this would lead to catastrophe.
0:47:03 > 0:47:10High winds and sun. A country without rivers and with little rain.
0:47:15 > 0:47:19Intensive farming techniques had weakened the structure
0:47:19 > 0:47:22of the soil till it could no longer hold itself together.
0:47:24 > 0:47:30So when a drought came the soil dried out then simply blew away.
0:47:30 > 0:47:33Turning the prairies into a huge dustbowl.
0:47:35 > 0:47:37The rains failed and the sun baked the light soil.
0:47:38 > 0:47:45It affected 100,000,000 acres of land. By 1940,
0:47:45 > 0:47:49over 2½ million people had been forced off the prairies.
0:47:51 > 0:47:54Their stock choked to death on the barren land.
0:47:54 > 0:47:58Their homes nightmares of swirling dust night and day.
0:48:00 > 0:48:01Many went to heaven.
0:48:03 > 0:48:06It was one of the biggest environmental disasters
0:48:06 > 0:48:08in American history.
0:48:10 > 0:48:15But today the problem is potentially worse than it ever was.
0:48:19 > 0:48:22There are now more than seven billion human beings on the planet.
0:48:25 > 0:48:27There are more of us alive today
0:48:27 > 0:48:29than there have been up to the 20th century.
0:48:31 > 0:48:35So it comes as no surprise more is being taken from the soil.
0:48:35 > 0:48:39We're more reliant on the soil than ever before.
0:48:39 > 0:48:44In trying to satisfy that need we're cultivating, tilling,
0:48:44 > 0:48:47fertilising to keep our soil productive.
0:48:47 > 0:48:52In doing so, we're destroying the delicate structural
0:48:52 > 0:48:56balance of the soil. That can be hugely costly.
0:48:57 > 0:49:01So when we talk about an impending food crisis
0:49:01 > 0:49:04what we should actually be talking about is a soil crisis.
0:49:08 > 0:49:13And that crisis is being felt as keenly in the UK as anywhere else.
0:49:16 > 0:49:20It's brought this farm in Ross-on-Wye to the brink of ruin.
0:49:26 > 0:49:30Asparagus farmer John Chinn has seen massive gullies
0:49:30 > 0:49:32open up in his fields.
0:49:35 > 0:49:40Weakened by farming, the soil was washed away by the rain,
0:49:40 > 0:49:42taking his crop with it.
0:49:46 > 0:49:49So what is it about the conventional way of managing
0:49:49 > 0:49:53a crop like asparagus that was causing that degree of erosion?
0:49:53 > 0:49:55It's two sides.
0:49:55 > 0:50:00The first is that we have soil exposed the whole time.
0:50:00 > 0:50:04Then, secondly, because we didn't want water standing in the crop
0:50:04 > 0:50:08we would plant the rows up and down the slope so the water would run off.
0:50:08 > 0:50:11Of course, what was happening was that the water was
0:50:11 > 0:50:15running off faster and faster and as it went it picked up the soil
0:50:15 > 0:50:20because it was just there on the surface. Carried that soil out to
0:50:20 > 0:50:24the bottom of the field, maybe into a stream, a road, leaving behind it
0:50:24 > 0:50:28a gully that as you came down the slope got deeper and deeper.
0:50:32 > 0:50:35We have an amber warning in force for the Somerset Levels.
0:50:39 > 0:50:43Water erosion has become a devastating problem in the UK.
0:50:45 > 0:50:49Could be another 20mm or perhaps a bit more in this area.
0:50:51 > 0:50:55Over the past five years, we've experienced an unusually high
0:50:55 > 0:50:59number of storms, culminating in the winter of 2013.
0:51:03 > 0:51:05It was the wettest on record.
0:51:06 > 0:51:10Vast swathes of the UK suffered rainfall on an almost biblical
0:51:10 > 0:51:15scale, leaving many areas like the Somerset Levels deluged for months.
0:51:21 > 0:51:24It's this kind of rainfall that was partly to blame
0:51:24 > 0:51:27for the destruction of John's asparagus fields.
0:51:31 > 0:51:33In desperation,
0:51:33 > 0:51:37he sought the advice of soil specialists at Cranfield University.
0:51:38 > 0:51:41One of them was Dr Rob Simmons.
0:51:42 > 0:51:47'He's investigating the huge problem of water erosion on the smallest
0:51:47 > 0:51:48'possible scale.
0:51:50 > 0:51:54'By studying the energy within individual raindrops.'
0:51:57 > 0:52:00The raindrop has a certain mass and a velocity
0:52:00 > 0:52:02which affects its kinetic energy.
0:52:02 > 0:52:08When that raindrop with that kinetic energy impacts on the soil surface
0:52:08 > 0:52:11it will damage the soil and cause breakdown at the soil surface.
0:52:12 > 0:52:17As you start to get extreme rainfall events you get short-duration,
0:52:17 > 0:52:21high-energy events with a larger drop size, more kinetic energy
0:52:21 > 0:52:24and they're going to cause more damage to your soil surface.
0:52:24 > 0:52:26And it's those that we're having more of?
0:52:26 > 0:52:29And it's those that we're having more of. Yep.
0:52:29 > 0:52:34Rob is testing what happens when rain hits soil.
0:52:34 > 0:52:38It's immediately apparent that excess water quickly starts
0:52:38 > 0:52:44to flow across the surface, what the scientists call run-off.
0:52:44 > 0:52:45Right, what we can see here is that
0:52:45 > 0:52:47run-off is being generated almost straight away.
0:52:47 > 0:52:50So expanded out onto a large field situation
0:52:50 > 0:52:53this could cause major problems.
0:52:53 > 0:52:55This is all well and good in a lab,
0:52:55 > 0:52:57but is there anything you can do about it out in the field?
0:52:57 > 0:53:01Absolutely, but the best thing to do is to go out in the fields.
0:53:01 > 0:53:04- Where the sun is shining. - Where the sun is shining.
0:53:04 > 0:53:09By understanding exactly what happens when raindrops hit soil, Rob
0:53:09 > 0:53:15has been able to help John make some big changes to the way he farms.
0:53:15 > 0:53:17And they're surprisingly low-tech.
0:53:19 > 0:53:22Instead of planting straight up and down the hillside,
0:53:22 > 0:53:25John now plants his rows on the diagonal.
0:53:26 > 0:53:29And he plants grass strips between them.
0:53:29 > 0:53:34The combined effect is to slow down the run-off of water,
0:53:34 > 0:53:36reducing its power to erode the soil.
0:53:37 > 0:53:40But that's only the beginning.
0:53:40 > 0:53:45Now Rob's come up with an ingenious new idea to take the energy
0:53:45 > 0:53:46'out of the rain itself.
0:53:48 > 0:53:51'To test it, he's set up rainfall simulators
0:53:51 > 0:53:55'and dug a series of channels, or wheelings.'
0:53:57 > 0:53:58We've got two rainfall simulators.
0:53:58 > 0:54:00We've got
0:54:00 > 0:54:02a wheeling which is bare on the left-hand side. And on the
0:54:02 > 0:54:06right-hand side we've got a wheeling which has got straw mulch in it.
0:54:06 > 0:54:11What the straw will do is it will absorb the energy of that rainfall.
0:54:11 > 0:54:14It will also act as a blanket effectively
0:54:14 > 0:54:17and it will absorb some of that water, slow down the run-off.
0:54:19 > 0:54:23It seems an incredibly simple solution, basic straw.
0:54:36 > 0:54:41Comparing the two scenarios side by side reveals a big difference.
0:54:44 > 0:54:48Raindrops hit the bare earth with force and break up the soil.
0:54:50 > 0:54:54Run-off water soon begins to flow and carry the soil away.
0:54:58 > 0:55:02But here the large drops are broken up before they can hit the ground.
0:55:03 > 0:55:07It's the straw, not the soil, that takes the brunt of the impact.
0:55:09 > 0:55:12And the run-off is reduced to a trickle.
0:55:14 > 0:55:17By having that canopy it absorbs all the energy, you don't have
0:55:17 > 0:55:20the detachment, you don't have the run-off and erosion problems.
0:55:26 > 0:55:30What's your reaction to the technology which is now being
0:55:30 > 0:55:33deployed in the field?
0:55:33 > 0:55:36Well, I suppose as a farmer it started off as scepticism,
0:55:36 > 0:55:40you know, here's a chap from the university. Yes, he can solve
0:55:40 > 0:55:44civil engineering problems, mining quarrying problems, but
0:55:44 > 0:55:45this is farming.
0:55:45 > 0:55:49And so it's taken a little while, I think, hasn't it, Rob?
0:55:49 > 0:55:55You've worked on me, you've shown me that it works. Now that's starting
0:55:55 > 0:55:59to snowball. That's going out to other farmers and I think that
0:55:59 > 0:56:03in 10 years' time the sort of things were doing now
0:56:03 > 0:56:05will become standard practice
0:56:05 > 0:56:09and frankly to not do them will become unacceptable.
0:56:09 > 0:56:11We have to look after the soil, it's a valuable resource.
0:56:18 > 0:56:22To me, it's astonishing that a potentially huge threat to soil
0:56:22 > 0:56:26can be averted using something as low-tech as straw.
0:56:28 > 0:56:32All it needs is a little thought and a willingness to change.
0:56:34 > 0:56:39I believe these are vital if we're to avoid the mistakes of our past
0:56:39 > 0:56:43and preserve this most precious of resources.
0:56:44 > 0:56:48And research like this and the commitment of farmers
0:56:48 > 0:56:51like John give me hope that we'll achieve that.
0:56:59 > 0:57:02So, whilst we have a chequered history when it comes to our
0:57:02 > 0:57:04relationship with soil,
0:57:04 > 0:57:09it does seem at last we're beginning to understand and
0:57:09 > 0:57:12appreciate what an amazing substance it is.
0:57:14 > 0:57:18'Exploring soil, we've uncovered the secrets of its life-giving force.'
0:57:20 > 0:57:25We've revealed an intricate living system, where life meets rock
0:57:25 > 0:57:28at the microscopic scale.
0:57:31 > 0:57:34Each acting on the other in complex
0:57:34 > 0:57:38and surprising ways to form what to me is, without doubt,
0:57:38 > 0:57:44the most fascinating and important material on the face of the planet.
0:57:44 > 0:57:47So the next time you walk on the grass
0:57:47 > 0:57:50give a nod of thanks to the hidden rainforest beneath your feet.