Soil is the literal foundation for much of life, yet we treat soil like... well, like
dirt.
Maybe that's because, most of the time, soil takes care of itself; decomposing plants and
animals and degrading bedrock produce new soil at roughly the same pace that wind and
water erode it away
But this balance between soil formation and erosion is easily tipped.
For millennia, the tiny Pacific island of Mangaia was covered in a thin layer of fertile
soil, but after humans arrived around 2000 years ago, their slash-and-burn agriculture
exposed the soil to the elements.
Over several centuries, rain and wind swept virtually all the nutrient-rich topsoil from
Mangaia’s hillsides and concentrated it in just a few arable valleys, which people
viciously fought over.
With less land to grow crops, people resorted to alternative food sources like rats—and
even each other.
We’re doing the same thing throughout the world today - not the part where we eat each
other, but the part where we farm the soil away.
That's because we make for agriculture by clearing away deep-rooted native vegetation
and use hoes, plows, and tractors to loosen the soil, making it easier for wind and rain
to sweep away.
And we grow mostly shallow-rooted crops that are no good at holding onto soil, and that
get stripped away during harvest, leaving fields bare for much of the year and at the
mercy of the elements
As a result, the world's farmlands lose soil 50 times faster than new soil can form.
That extra erosion adds up to about 8 billion pickup trucks of soil moved annually from
fields to places like the bottoms of rivers and behind dams - which are less convenient
for farming.
That soil loss reduces global crop yields by as much as if we took a California-sized
swath of farmland out of production every decade.
Fortunately, we know how to bring erosion back into balance with the rate at which soil
forms: plow less often, and after harvest, leave plant parts behind or plant so-called
cover crops to, well, cover the soil as protection against water and wind.
We can also incorporate trees or native plants that keep soil in place year-round.
Putting strategies like these in place can cut erosion by as much as 95 percent, helping
keep crop yields high in the long run.
But in the present, they can hurt yields, because adding other vegetation to farm fields
means less room for crops.
As a result, we’ve been slow to make these soil-saving strategies the norm.
If we can’t keep the farmable soil on our farms, human civilization won't immediately
implode, but we might end up fighting over the patches of land where that soil ends up,
like the Mangaians, but on much, much bigger islands.
And, speaking of soil, this video was sponsored by Soylent, a line of nutritionally-complete,
convenient foods that actually take less Soy-l to produce because many of their core nutrients,
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