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)
