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MILES O'BRIEN: This tiny sensor could revolutionize the way
farmers around the world fertilize their crops.
CALDEN CARROLL: The little black bar has on its surface a
chemical receptor for nitrate, and nitrate sticks to that
receptor and then that sensor can read the amount of
nitrate that's there.
MILES O'BRIEN: With support from the National Science
Foundation, organic chemist Calden Carroll is a co-founder
of SupraSensor Technologies, a startup company that's
developing a novel sensor to detect nitrate
fertilizer in soil.
CALDEN CARROLL: So soil fertility really has to do with
N, P and K -- nitrate, phosphorus and potassium. Anybody that's
done any gardening has probably seen fertilizers that have N-P-K
values on there.
MILES O'BRIEN: Over-fertilization is a huge
problem in commercial agriculture.
CALDEN CARROLL: So as you irrigate, as it rains, that
water pushes down through the soil, through the root zone and
actually pushes the nitrate down below the root zone out of the
reach of the plants.
MILES O'BRIEN: About 30 percent of nitrate fertilizer applied to US
crops washes away. The SupraSensor device is designed
to give farmers a highly accurate, virtually constant
stream of data on nitrate levels. Highly applied science
with roots in basic research.
DARREN JOHNSON: You can't always predict when you might
make an exciting discovery…
MILES O'BRIEN: Ground work for the SupraSensor device was done
here at the University of Oregon. Team member Darren
Johnson works in the field of "supramolecular" chemistry.
DARREN JOHNSON: Supramolecular chemistry is a simple idea of
how two or more molecules might interact or bind with one
another without forming strong irreversible interactions.
MILES O'BRIEN: A supramolecular interaction is key to how the
nitrogen sensor works.
DARREN JOHNSON: So if we pretend nitrate is a baseball
and our host molecule as a mitt, the nitrate binds into the mitt
and now the mitt changes color and all of a sudden
glows; it fluoresces.
MILES O'BRIEN: Mike Haley is the team expert on fluorescence
chemistry. He says the challenge was how to turn a
flash of light into a signal that can be recorded by a probe
buried in soil.
MIKE HALEY: Probably the key discovery on the SupraSensor
side was how to make that optical response into
an electrical response.
MILES O'BRIEN: They've also developed electronics to store
data, wireless capability, different form factors -- even a
smartphone app. As the global population booms, scientists
will need to come up with higher yield methods to feed more
and more people.
MIKE HALEY: Farmers want to be good stewards of the land and
they unintentionally over fertilize...
MILES O'BRIEN: Wasted fertilizer is
wasted energy, literally.
MIKE HALEY: So, of the 2 to 3 percent of the world's energy that is
used to make ammonia, half of that is used to make ammonium
nitrate fertilizer. About 30 percent of that is over-fertilized. So,
conservatively you can say we're throwing away about a half of a
percent of the world's total energy.
MILES O'BRIEN: The SupraSensor team hopes to help turn the tide
toward a new era of precision agriculture, saving time, money
and the environment along the way. I'm sensing a winner!
For Science Nation, I'm Miles O'Brien.
