February 2024 - 9

acres in the state are under irrigation, which means some
genetic tolerance is crucial to the crop's success.
To test for tolerance to water stress, new varieties that come
out of UMaine's breeding program are sent to North Carolina
and Florida, where they are selected for heat resistance.
This is done through a strategic partnership between seven
institutions, including Penn State, Virginia Tech and Cornell.
The partnership was developed 20 years ago.
" In the U.S., we always try to have a potato that can grow
in a wide range of places, " Andrade said. The partnership, he
added, allows them to do this.
To date, the program's most successful cultivar is Caribou
Russet, a variety that farmers have said shows good resistance
to drought and heat, Andrade said.
MITIGATING WATER QUALITY ISSUES
At the University of Wisconsin-Madison, associate professor
and state Extension specialist Yi Wang focuses on sustainable
vegetable production. This includes water management in
potatoes. While earlier research efforts focused on drought
tolerance, following a very wet year in 2018, the program
switched gears and targeted water quality instead.
According to Wang, most of Wisconsin's potatoes are produced
in the Central Sands Region, which has sandy soil. Organic matter
is less than 1%, which means water-holding capacity is extremely
low. When precipitation surpasses 1 inch, either from rainfall or
irrigation, everything leaches down to the groundwater table. The
region's groundwater table is very low, said Wang.
In some places, it's as shallow as 10 feet to 20 feet from the
soil surface. On top of that, potatoes are a very needy crop
when it comes to fertilizer.
To avoid nitrate leaching, Wisconsin Extension specialists
like Wang recommend growers split apply 250 lbs of nitrogen
per acre, per growing season - 60% at planting, and 40% at
the early-to-late tuber bulking stage.
" The split nitrogen application is more for avoiding the
nitrate leaching issue, but even with that we are still facing
potential nitrate leaching, " Wang said.
One of the solutions has been to use ESN, a slow-release
nitrogen fertilizer. Producers have still reported issues with
leaching, though, she added.
Wisconsin researchers are also using remote sensor
technology and machine learning, including hyperspectral and
multispectral imaging and ground-based robots, to monitor
plant growth and improve weather forecasting. Having access
to more accurate data allows farmers to make better use of
decision-making tools like the 4R Nutrient Stewardship plan.
Applying the right fertilizer source at the right rate in the right
place at the right time could, ultimately, help farmers reduce
nitrate leaching potential.
" Potatoes need nitrogen, and our system doesn't hold nitrogen,
so how do you find a balance? " said Wang. " That's the question
we're trying to address right now with different strategies. "
BENEFITS FOR PRODUCERS
All water is not created equal; there are distinct differences
between rainwater and irrigated surface or city water. Normal
irrigation water can be hard due to high sedimentation and
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February 2024

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