Put carbon where it belongs… back in the soil

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(narrator) We hear a lot about
climate change and carbon dioxide.

What can farmers do about it?

"A lot," says Australian soil scientist
Dr. Christine Jones,

"and get better crops as a result."

It's all about getting light energy,

transforming it to biochemical energy,

getting that biochemical energy
into the soil,

to drive the soil ecosystem
to make nutrients available.

Well, the reason carbon is important

is because all living things
contain carbon.

So as things live and die,
they give up their carbon

and then something else lives
and takes up that carbon.

I guess what we're talking about
with climate change is,

we're talking about that cycle
getting out of balance.

So for thousands of years,
it's been in balance...

the atmosphere
and the plants, and the soil,

and all the living creatures.

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(narrator) But in modern times, people
have dug up and burned fossil fuels,

and exposed soil for farming.

In fact, over a third of the carbon

added to the atmosphere since 1850

has come from deforestation and exposing,

and oxidizing
the rich carbon deposits in our topsoil.

U.S. soil scientist
Dr. Elaine Ingham says,

"We can put it back though,

and in a way
so that much of it will stay."

So, carbon sequestration,
we're talking about putting CO2

from the atmosphere back into the soil

in a form that's not going to be lost.

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(narrator) How do we do this?

The same way nature did
in the first place.

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We've got to be photosynthesizing,

so we've got to be
growing plants in that soil,

so CO2 and sunlight
will be bound back into sugar structures.

As those sugars go down
into the root system,

picking up all the nitrogen, phosphorus,
sulfur, magnesium, calcium

from the soil.

Building that plant material.

The plants are putting
exudates out into the soil,

"cakes and cookies" out into the soil,

and the bacteria and fungi
utilize that material

and build the organic matter
back in the soil once again.

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(narrator) Those sugar water exudates
are the key.

This photo shows liquid carbon
flowing from a plant root above,

along a fungal hypha or two,

to feed the fungus below.

In exchange for that carbon,

soil microbes, including fungi,

bring water
or micro nutrients to the roots,

causing the plant to release more carbon.

In order to build that soil carbon,

you have to be looking after the microbial

or supporting
the microbial communities in the soil

that join all the little
carbon atoms together

to form humus polymers.

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I can't grow as well unless
those microbes are there.

They won't have as many
trace elements in them

if those microbes aren't there.

And when the plants don't have
those trace elements in them,

they become vulnerable
to insect attack and fungal attack,

pathogens of all kinds.

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Finally, we're now seeing
the light as it is

and realizing that we are light farmers.

And that what we need to do

is to harvest as much
sunlight energy as possible

by having as much green leaf as possible.

Therefore, as much
of the year as possible.

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(narrator) Because photosynthesis
drives the whole system,

soil should always be covered with plants,

either crop plants or cover crops.

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Farmers here in the United States

started experimenting with two-way covers,

and then five-way covers,
and then ten-way covers,

and now they're sort of aiming
for 20-way covers.

In other words, 20 different varieties
of plants in a cover crop.

And realizing that the more diverse
they make the cover crop,

the faster they can build soil,

and the more-- less reliant
they are on any chemicals at all.

(narrator) Farmers are finding
that building soil biodiversity

builds plant health.

And they're finding they don't have
to use any synthetic fertilizers anymore,

they don't have to use pesticides,
they don't have to use insecticides.

Not only are they producing food
that's higher in nutrients,

but it's also lower in toxic chemicals.

And they're taking CO2
out of the atmosphere

and storing it in the soils.

(narrator) We also
want resilience in our fields.

Carbon builds
a good, clumpy soil structure,

holding on to rainwater.

And the other thing is how quickly,
when the rain does absorb,

how quickly does it evaporate?

So when it gets into the soil,
we want it to stay there.

So we want to have aggregates in the soil,

which are little lumps,
like pea-shaped lumps in the soil

that have a much higher moisture content

on the inside of the aggregate
than on the outside.

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And we see the greatest increases
in carbon sequestration,

through what I call
the liquid carbon pathway--

when it's being fixed in green leaves,
translocated through the plants,

exuded by roots
into microbial communities in the soil,

and forming aggregates,

and leading to the process of unification,

which is the "holy grail" for soil,

to have an increase in humus in the soil.

(narrator) So our job,
as Dr. Ingham says, is to farm

so we are working with nature.

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(Elaine) So don't till.

Could we have a list of those farmers

that are no-till or zero till

and really let people know that

they're the ones doing the work?

(narrator) And, as Dr. Jones says, this
kind of farming is a win for everyone.

(Christine) If we can take more
of the carbon that's in the atmosphere

and store it in our soil,

then our soils
and our food production systems

are going to be more resilient.

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But we could produce the same meal
with much higher quality,

with much lower cost,

and building soil at the same time.

I think the fundamental shift
in thinking that we have to make

is that farming is about harvesting light.

Through the process of photosynthesis,

we're going to change light energy
to biochemical energy,

and then that biochemical energy
becomes our plants, our animals.

So, you know, through the carbon compounds

that are made by that process.

We are fundamentally light farmers

and when we make that realization,
then the sky's the limit.