Hi, this is Alex from MinuteEarth.
Farmers are obsessed with water. It makes sense.
Their livelihoods depend on crops that will die without enough water.
So lots of farmers buy expensive equipment to pump tons of water to their fields.
In fact, of all the water humans use, 70% is for agriculture.
But here’s an even crazier thing,
lots of farmers also spend tons of effort, and tons of money, dewatering their fields.
That’s because too much water is also deadly for crops.
All plant cells need oxygen to function.
The cells above the ground take it from photosynthesis or from the air around,
and the cells underground take it from tiny air pockets in the soil.
But if the soil is too wet for too long, the roots can literally drown, killing the entire plant.
Plus, wet fields cause tractors to get stuck and to compact the soil,
另外 湿土会让拖拉机下陷 使土壤更密
which reduces both the amount of air in the soil and the space for roots to grow.
To save their crops from these problems,
farmers around the world have dug ditches
and installed special underground pipes to drain excess water away.
As a result, the soil has enough space in it for roots to grow
and enough air for roots to breathe.
Crops survive, tractors don’t get stuck, and overall productivity increases.
庄稼存活 拖拉机不陷于泥 总产量增加
However, draining water away more quickly means
that it reaches nearby streams and rivers more quickly,
where it can speed up the flow and contribute to floods.
And floods can damage infrastructure and erode river banks and river bottoms,
creating deep channels and muddying the water downstream.
Plus, the water coming from the fields can carry chemicals from fertilizer and pesticides
which end up polluting rivers, lakes and eventually, oceans.
会污染河流 湖泊 最终污染海洋
These problems caused by drainage can be mitigated somewhat
by applying fertilizer and pesticides precisely where and when the crops need them.
We can also send the water through trenches filled with wood chips or buffers of native plants,
both of which can filter out some of the chemicals before the water flows into a nearby stream.
And we can also retrofit the underground pipes to slow down the flow of water
when it’s ok to have a wet field
like when we’re not gro wing crops.
But there is another huge problem with drainage
it’s helped us turn wetlands into farms.
Wetlands are incredibly valuable,
because in addition to providing habitat for fish, birds, and other creatures,
they also act like giant sponges that prevent floods
and filter the water making it cleaner for everyone downstream.
In the last 200 years, over half – and maybe even over ¾ – of the world’s wetlands
最近的200年 超过一半 甚至可能超过3/4的世界湿地
have disappeared and been replaced mostly with farmland.
So, thanks to drainage we get new and more productive farmland,
which helps us grow lots of extra crops.
But we also lose wetlands and gain some new problems.
And unfortunately, gaining the benefits without any of the downsides may be a pipe dream.
This video was sponsored by the University of Minnesota
where students faculty and staff across all fields of study
are working to solve the grand challenges facing society.
One of these challenges is assuring clean water and sustainable ecosystems
and part of the solution is to reduce the amount of pollution from agriculture runoff.
Professer Jacque Finlay and postdoc Christie Dolph in the College of Biological Sciences along with collaborators
生命科学学院的Jacque·Finlay教授和博士后Christie· Dolph 以及他们的合作者
have found that if we restored wetlands in strategic locations where they could intercept lot’s of water
they’d be three times more effective at removing pollution than wetlands restored elsewhere.
Professor Michael Sadowsky in the Department of Soil, Water, and Climateis
土壤 水源及气候系的Michael· Sadowsky教授
is identifying the bacteria that remove chemicals from water sent through woodchip trenches.
And Adjunct Professor Heidi Peterson in the Department of Bioproducts and Biosystems Engineering
is collaborating on a project to filter and retain drainage water using a wetland at the edge of a field.
Thanks, University of Minnesota!
Hi, this is Alex from MinuteEarth.