Transcriber: Hilda Chan Reviewer: Rhonda Jacobs
So centuries ago, Leonardo da Vinci said,
"We know more about the movement of the celestial bodies
than about the soil underfoot."
Today, more than ever before,
we need to understand what's happening beneath our feet.
Limited access to clean water, food production for a growing population
and extreme weather conditions are impending crises
all rooted in our treatment of the soil.
It's not time to panic, but it is a time to make some serious changes.
And it's time to stop treating our soil like dirt.
(Laughter)
So, I understand that a lot of us have a hard time
differentiating between soil and dirt so I brought some with me.
So this is soil.
It's a mix of sand, silt and clay and maybe some gravel, air, water, humus
and trillions of microbes, bacteria, fungi, nematodes, worms and beetles.
All this life beneath our feet.
And this is an underground universe
that's a complex ecosystem we're just starting to understand,
but the beings in this soil are busy
breaking down chemical compounds in plants, and feeding roots,
and filtering and storing water, and sequestering nutrients.
So that's soil.
And then, I've got some dirt too.
So that's dirt.
Okay.
So -
Alright, so now that we've got that sorted out, let's talk about soil.
So, soil's formed over many, many, many thousands of years
from rocks breaking down, plants decomposing,
rivers depositing sediment, wind blowing in silt and volcanic ash,
oceans and glaciers advancing and retreating,
but land is a limited resource and soil is its fragile skin,
so when we let it wash away or blow away, or we compact it or contaminate it,
it doesn't regenerate quickly.
So we're losing our soil. We're mining it.
Or we're just paving it over,
and that's a problem because we lose some of the natural processes
that we've relied on.
So I want to talk about three ways that soil plays a vital role in our lives.
And first let's talk about something pretty fundamental like water.
So, we're already fighting over water, right?
Even in Alabama we have an abundant water supply,
but we're competing with Tennessee and Gerogia and Florida over water rights.
In California there's a drought
that's pitting farmers against cities and home owners.
And over 800 million people in the world don't have access to clean drinking water.
Now, soil is the Earth's water filtration system.
So when it rains or snows or floods,
water can either seep into the soil or it can wash away.
The water that seeps into the soil is filtered.
It carries some compounds with it that filters through
and enters the ground water, clean and ready to use again.
The water that runs off carries with it not only soil
but contaminants - pollutants from roads,
fertilizers and pesticides from farmers' fields,
and those accumulate downstream,
so that's what causes the dead zone in the Gulf of Mexico,
and that's why the city of Toledo had to cut off its water supply
this summer.
And wetlands are the Earth's best water filtration system,
but we're losing wetlands at an amazing rate.
We lost 2/3 of the global wetlands since 1997,
so it's 250 million acres.
So now we've got water that's becoming a limited resource,
and we're losing our natural ability to filter it.
Okay. So that's just one vital role.
Along with water, we also need some food,
so - and soil feeds us,
and we all know that, right?
Okay. That's the easy one.
But we need to feed a growing population that's projected to reach 9 billion people
by the year 2050.
And those people are eating higher on the food chain,
so that's more meat, less rice and beans, and that's more resources per calorie.
In the mean time, we're losing all this soil to erosion.
The last year, they lost 1.7 billion tons of soil
on cropland in the United States in a single year.
And we're doing better than some other countries.
And nitrogen fertilizer
is based on the fossil fuels that we have a limited supply,
and we have a peak phosphorus crisis that you probably haven't even heard of.
Our crop yields are increasing, but their nutritional value is decreasing.
We treat our manure like toxic waste instead of fertilizer,
and we throw away almost as much food as we eat.
So, that's not really a sustainable strategy,
so we need to be looking at long-term soil productivity.
And that's what I get to do. I'm really lucky.
I get to work with farmers and scientists that are working to build healthy soils
that are deeper and more porous,
and can produce more nutritious food per acre or square foot or hectare.
And so on our farm and on farms like ours,
we do things like plant cover crops and rotate our crops,
and we minimize the use of tillage
and we inoculate the soil with compost and worm castings,
and we minimize the use of chemicals to build that soil food web
and let the microbes do the work for us.
And it works.
We've seen it, and it goes by a lot of different names:
permaculture, organic farming, no-till farming, biodynamic,
and the philosophies definitely differ
but the ultimate goal is to build healthy soils.
So if we can do that,
if we can focus on filtering water and feeding people,
then the third vital role of soils falls into place
because soils can help to mitigate climate change.
Healthy soils are resilient,
so they can buffer the effects of extreme weather.
They're like a sponge,
so if it rains too much, that water seeps through;
but if it doesn't rain enough, it holds more water in place
so it can keep a crop growing for longer.
And that's on the farm scale.
On the atmospheric scale,
well, we have excess carbon in the atmosphere, right?
Carbon is an essential soil element so we need it in our soil.
So instead of injecting it into the Earth's core
or blasting it into space,
let's take that excess carbon and store it in the soil where we can use it.
It just seems like a pretty easy answer to me.
So, I hope you understand that soil is not a cure-all.
It's a key factor in the solution though.
And I understand that most of you are probably not farmers
or caretakers in wetlands or environmental engineers,
so what can you do?
Well, proactive policy can go a long way towards solving these problems,
and we need more advocates for soil.
We're starting to see change:
the USDA is talking about healthy soil like never before;
at the UN, just 2015 they've named the International Year of Soil,
so I hope you all join me in celebrating that.
(Laughter)
But a lot of what you can do is on the local level.
Land management decisions are made more locally,
so planning and zoning, waste management, farmland conservation,
those are all things that happen on a local scale
and you can get involved and make a difference.
Or maybe you're already involved,
and maybe you're just not thinking about soil like you might should be.
The other thing that you can do that a lot of people are doing
is just growing their own food:
a plant on a window sill,
a garden in your backyard or an empty lot,
or even outside at your local school, like here.
And they see what soil can do for them if they treat it right.
And you know what? They stopped treating their soil like dirt.
So give it a try.
If you start to like soil, you might not even mind dirt so much.
(Laughter)
Thank you. (Applause)