The Hidden Wonders of Soil | Jane Zelikova | TED

71,589 views ・ 2022-08-16

TED


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Under our feet,
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there is an unseen world
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more diverse than all the tropical rainforests combined.
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Teeming with microbial life and critters, large and small,
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this hidden world of soil is on every single continent.
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But most of us know little to nothing about this vast world under our feet.
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And for most of my life,
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I was no exception.
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I grew up [a] very curious and adventurous kid.
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I spent a lot of time climbing trees and falling out of them.
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And I spent a lot of time getting really dirty.
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In college, I had to take a class for a science requirement,
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and I was shocked to discover that being really curious
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and loving dirt could be a legitimate career.
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So it took no convincing whatsoever for me to change my major,
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and that's how I became an ecologist.
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In graduate school, I studied how the loss of a seed disperser,
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in this case, the winnow ant,
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affected the plants that they disperse.
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In my research site,
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we were discovering that these ants were moving up in elevation
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to escape a rapidly changing climate.
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But they were leaving the plants they dispersed behind.
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So while I came to grad school to study ants,
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I all of a sudden found myself studying climate change.
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And because ants nest in soils, I had to learn a lot more about soil.
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What I couldn't have predicted, as that young, curious, budding ecologist,
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was that I would spend the next decade of my life
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thinking about the invisible army of soil microbes
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and how we can harness their awesome powers
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to help address climate change.
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But before we get to all of that, let's start at the beginning.
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Soils are considered to be the skin of the Earth.
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They're only a few meters thick,
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but they support all agriculture and every single terrestrial biome.
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Soils help protect our food supply,
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clean our water, boost our immune systems,
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and they serve as a source for some critical medicines,
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including many that have yet to be discovered.
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Without Earth's exceedingly thin layer of soil
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and its multitude of organisms,
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we would not eat,
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and humanity as we know it may not exist.
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And soils, like many good things, they take time to develop.
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They form over hundreds to thousands of years
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as rocks break down
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and plants and animals decompose.
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As soils form, they accumulate and store carbon.
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In fact, there are billions of tons of carbon stored underground.
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Two to three times more than what we have in the atmosphere.
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Plants and soil work in collaboration
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to drive the single most important transformation of carbon on this planet,
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photosynthesis.
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Plants take carbon dioxide from the air,
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and they combine it with water and sunshine to create sugars.
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And of course, to grow plants.
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Plants and their sugars eventually decompose in the soil,
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feeding the microbes.
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In fact, most of the carbon that comes in through plants
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ends up in soil at some point.
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The carbon cycle continues.
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Microbes and their carbon eventually break down,
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and the carbon from the microbes sticks to soil particles,
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creating what we call soil clumps or aggregates.
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Because microbial carbon is sticky.
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So when that microbial carbon ends up in a clump,
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it's physically protected from further decomposition.
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And what we know now
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is that the majority of soil carbon that is sequestered
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is actually dead microbes
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or what we call microbial necromass.
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That necromass can stick around in soils for decades to millennia,
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especially if we leave soils undisturbed.
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But over the last 12,000 years,
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we have lost billions of tons of carbon from our soil
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as humans converted grasslands and forests
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into agricultural fields and range lands,
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building roads and cities.
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One of the major drivers of that loss was the plow,
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which, at the time, was a major technological breakthrough
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that really revolutionized agriculture
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and altered the trajectory of human history.
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With each pass of the plow,
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those plant roots and soil aggregates that we know are really important
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are broken apart, exposing carbon to decomposition.
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Today we use more than a third of our land
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to feed and clothe billions of people on this planet.
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But we're losing our soils at an alarming rate,
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and with it, we're losing their fertility.
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Without that soil,
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it's going to be a lot harder to feed
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what is going to be close to 10 billion people
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on this planet by 2050.
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That's going to put a lot more pressure
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on what is already a disappearing
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and resoundingly underappreciated resource.
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There is no machine that can bring soil back.
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No technology that can do what thousands of years of rock weathering
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and biological activity have achieved.
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But we can build our soils and put more carbon underground
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with a little help from plants and microbes.
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Rebuilding soil is going to require us to fundamentally rethink our reliance
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on technology and chemicals
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to deliver what soils can do on their own:
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support life.
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And life in soil is mostly microbial.
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The Dutch scientist, Antoni van Leeuwenhoek,
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saw tiny organisms he called the "wee beasties,"
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under his microscope about 350 years ago.
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And with the rapid innovation of molecular and computational tools,
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we are finally getting a sneak peek at who they are
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and how they make their way in the world.
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Here's the thing.
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A teaspoon of soil holds billions of organisms,
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things like bacteria, fungi, protists and archaea.
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These microbes are the movers and shakers
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of nature's carbon cycle.
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They drive really important processes in soil,
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they take organic matter
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and convert it into complex carbon molecules.
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And having more carbon in soil is transformative.
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As carbon accumulates,
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agricultural fields can hold on to more water and more nutrients,
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building resilience that helps them
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deal with the ups and downs of a changing climate.
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That resilience means plants can grow more consistently,
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even when the weather is fickle.
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And the awesome thing is carbon-rich soils help buffer us
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against what is an uncertain climate future.
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The trick is to really rethink how we do agriculture.
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So there is the good news,
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which is there are some tried and true ways
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that we can get more carbon in our soils and build our soils back.
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We can plow less,
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and we can make sure that we have roots in the ground year round,
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feeding the microbes
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and powering that microbial engine humming under our feet.
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And we can do this.
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The other thing is,
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diversity is the key ingredient in this recipe.
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Diverse plant communities support diverse microbial communities
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that can transform and store more carbon.
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Diversity is good for soils,
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and it's good for climate mitigation.
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Just like we need every microbe,
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we need every farmer and rancher,
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every climate solution and every solver.
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So ...
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Healthy, carbon-rich soils matter today more than ever.
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The other great thing about carbon-rich soils
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is they help farmers have more consistent agricultural operations
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and more sustainable ones
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that can withstand the ups and downs of a changing climate.
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That's a huge win for the people that grow our food,
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it’s a win for climate, and it’s a win for us consumers.
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So how do we do it?
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Well, there are three simple things we can do.
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Number one, we have to protect our soils and the carbon they already hold.
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Number two, we can get more carbon underground
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by growing diverse, climate-adapted crops.
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And number three, we can let the microbes do their thing.
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Leave them alone by leaving the soil undisturbed.
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It sounds simple, and that's because it kind of is.
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But there are some questions that are left to be answered,
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and there's a lot of room for us to innovate.
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We need to track and measure our climate progress.
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We need to develop more climate-resilient crop varieties
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that can grow deeper roots
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and pump carbon underground deeper.
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And we need to rethink our economic models and agriculture
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and help support and incentivize
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these carbon-sequestering agricultural practices.
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So lots of room for innovation, lots of room for research.
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Good news for us scientists.
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But we don't have time to waste.
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Climate change is here and it's affecting all of us, whether we know it or not.
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It's affecting every single ecosystem, including agriculture.
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Soils are the literal foundation of life on this planet,
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the reason that we can eat
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and the climate solution just waiting to be unlocked.
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So let's build back our soils,
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help our planet by looking down to the ground.
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Thank you.
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(Applause)
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