This is my compost bin. It’s where I put
used coffee grounds, melon rinds, corn husks;
pretty much anything that was a plant in its
former life, along with shredded up newspapers,
junk mail and pizza boxes. If I wait long
enough, something kind of amazing happens.
All that stuff is transformed into, well, what
looks like ordinary dirt. But this dirt is
anything but ordinary. This dirt is alive.
Yes, it’s full of earthworms. We’ll get
to them. But it’s also full of millions
of tiny creatures that you need a microscope
to see. You wouldn’t know by looking at
them, but these little guys hold the key to
human civilization. Without it, human life as we
know it wouldn’t be possible. Which makes
it all the more puzzling when you discover
that its number one enemy is us.
So, not all dirt is created equal. It can have more or
less of those little living creatures in it.
And there’s an easy way to tell even if
you don’t have a microscope at home.
First, put about a handful of dirt in a clear glass jar. This
is some soil I collected from the worm bin.
Don’t worry, I took out the worms later.
And this I dug up from my backyard.
Next, add some water. Screw the lids on nice and
tight, and shake them up. And now, we wait.
OK, it’s been a day, we’re back, and we
can see that both of our samples have separated
into distinct layers. You can see that they look really different.
Let’s look closer at the dirt from the backyard. It has a bunch of stuff
on the bottom: gravel, sand, silt, and clay.
This stuff floating at the top is called humus.
That’s where all the microscopic creatures
live. Scientists call them microfauna: micro
for small, fauna for animals. There are millions
of different kinds. When old plants die, the
microfauna eat them and then, well, they
poop. That waste is full of nutrients that
new baby plants need to grow. Grass, tomatoes,
apple trees--- no matter the plant, the process
is the same. And the more microfauna there
are in the soil; eating, pooping, doing their
thing… the bigger and healthier the plants.
Over millions of years, the new plants would
use up nutrients in the soil, then the microfauna
would replaced those nutrients by eating the
dead plants. In mild climates, the microfauna
could build up about two and a half centimeters, or one inch
of humus every 500 years. Evolution continued
and eventually produced a species who changed
this process forever.
Homo sapiens have been
around for almost 200,000 years, but we didn’t
start farming until about 12,000 years ago.
Before then, we still depended on healthy
soil for food. The grass that fed the herd
animals we hunted,  the nut trees and berry
plants we foraged… these all grew from the
rich humus that the microfauna created.
Farming developed at various points in time,
in different regions of the world. And from
the beginning, some of those early farmers
recognized the relationship between healthy
soil and healthy plants. Like the Iroquois
in the eastern part of what is now the United
States. The first farmers there,  women,
by the way, planted corn atop mounds of
soil every spring. After they harvested the
corn in the fall, they left the dead cornstalks
atop the mound. All winter long, the microfauna
broke them down into nutrient-rich humus.
The next spring’s new baby corn plants would
use those nutrients and start the cycle again.
Iroquois farmers would also plant beans and
squash in the same plot. Together, these three
crops were known as the “three sisters.”
Not only did this combination make for a balanced
diet of protein, carbohydrates, and crucial
vitamins for the Iroquois people, it also
kept the microfauna in the soil happy, healthy
and pooping. Early farmers in other parts
of the world developed different ways to feed
the soil. Like in the Amazon river basin.
Early farmers there used controlled fires
to create patches of rich humus.
Today, if you dig deep into that soil, you can see that its much darker and healthier
than the regular tropical soil nearby.
All over the world, the
earliest farmers found ways to care for the
soil so that it would produce healthy plants.
But slowly, as European colonists descended
on various parts of the world, these ancient
practices gave way to a new type of farming.
Machines like the steam engine and the power
loom transformed life in Europe, and then in North
America, starting in the mid-1700s. The lure
of factory wages drew people from the countryside
into cities, which meant the farmers who stayed
on the land needed to produce more food to
be shipped to the cities. Farmers got stuck
in a cycle of constant harvesting, without
giving the soil time to regenerate the nutrients
it had built up over generations. The soil
quickly wore out, so they responded by cutting
down forests and turning them into fields.
In North American, European settlers used
violence to push the Iroquois and other indigenous people further west,
away from the three sisters fields that had
sustained them for thousands of years. When
they stripped that soil of its life, the settlers
kept moving west, seizing indigenous lands
along the way. New steel plows helped them
break up the hard, heavy soils of the Great
Plains. But these new steel plows did something
else. They turned up the soil over and over again, which killed
a lot of those microfauna that had been living
in the soil making humus. And when gasoline-powered
tractors showed up in the early 1900s, their
weight pressed down on the increasingly lifeless
soil, making it even harder for plants to
grow. By the 1930s, the soil of the Great
Plains had lost so much of its microfauna,
giant dust storms pummeled the region. Thousands
of families lost their farms. This new
type of farming wasn’t limited to Europe
and North America. The small farms that had
sustained the indigenous peoples of Central
and South America for generations had been
replaced by giant mega-farms, haciendas, run
by the Spanish and Portuguese settlers and
worked by indigenous and enslaved people.
the crops didn’t feed the people there. These
fields were full of sugarcane and cotton to
be shipped out of the country to factories.
And, just like in North America, the overworked
soil quickly crumbled and started to wash
away. In response, farmers around the world
started to rely on chemical fertilizers, which
help crops grow quickly, but can also pollute
drinking water and kill fish and other types
of aquatic life. According to the United Nations,
practices like this are killing the humus
so quickly, we may run out of healthy soil
in less than 60 years. That is, if we keep
doing things the same way.
Remember the soil we tested, that these guys helped to make?
Look at it next to the jar of backyard soil. See how there’s way more humus floating
on the top? More of this stuff is exactly
what we need, all over the world, to replace the soil we’ve already destroyed.
And earthworms can help.
On farms where years of plowing has damaged the soil,
a handful of farmers have stopped doing it.
Instead, they roll down the old crop then
use a series of drills to plant the new seeds
underneath the old crop. Because this method
doesn’t disturb the soil, it gives earthworms
a chance to make humus, and to create tunnels
that help water get to plant roots. It also
helps to loosen the soil so that plant roots
can spread. But this method has been slow
to catch on. Just one in four American farmers
use it. On many smaller farms, though, earthworms
are a big part of the operation. This is our
worm bin. These are the hardest workers, these
are actually red wriggler worms. This is Marc
White. He showed me around his urban farm,
right in the middle of Cleveland, Ohio.Here
are the raspberries I talked about. Just pull
one off right there. Oh my gosh. Isn't that awesome? Everything is based on the soil. Everything that
we eat is a reflection of the soil.
This right here, this is the black gold.
On Marc’s farm, that process starts here, in the compost
pile. Over time, wood chips and food waste
break down with the help of earthworms and
microfauna.
So this is how the soil you saw inside, this is how it starts out.
In the next 10, 15, 20 years, this whole footprint
will have been improved so much more for us
having been here.
We need healthy soil to
grow healthy food, and we need healthy food
to grow healthy people. It’s all connected.Dirt
is so much more than the stuff beneath our
feet. It’s the stuff of life. And the sooner
we realize that, the better off we’ll be.
