WINNIPEG – In the past five years, Pete Carson has reduced fertilizer
use by 37 percent on his 1,500 acre farm. In that time, his wheat
yields increased by 35 percent and he has gained a price premium on his
sugar beets.
Carson farms at St. Thomas, North Dakota, just south of the
Canada-United States border. He has a typical rotation for his area,
with sugar beets, wheat and potatoes.
In 1994, he was one of the first producers in North America to make a
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
serious attempt at putting precision farming into practice.
Today, Carson has no doubts about whether precision farming works.
“On one 74 acre field, I saved $13,000 over the 2001 and 2002 crop
years. To accomplish that, we use topography maps, yield maps,
electrical conductivity maps, satellite imagery and anything else that
might provide information about a field.”
He said sugar beet tops put an enormous amount of nitrogen back into
the soil, but not all at once. His big challenge was to figure out a
way to account for those nitrogen credits in the years following sugar
beets.
“Scientists doing work on our farm found that decomposition of the
sugar beet canopy is only 80 percent complete by the following May.
Mineralization takes that long. So, even if I wait until the next
spring to do my soil sampling after a sugar beet crop, I’m still not
getting an accurate recommendation.
“The lab says we have only 10 to 15 pounds of nitrogen in the top two
feet of soil. So, going strictly by their recommendation, we should add
180 lb. additional nitrogen for a target of 70 bushels of wheat. But we
know that recommendation is wrong, because the sugar beet tops can
easily give us another 100 lb. of nitrogen for the subsequent crop.”
Carson uses satellite imagery to map the sugar beet canopy. The shade
of green in the canopy helps determine the management zones for the
wheat seeded the following year.
“The reflectance value of the sugar beet tops is easily detected and
mapped by the satellite,” he said.
Lush, dark green tops are rich in nitrogen. As the tops move closer to
yellow-green, there is less nitrogen available to be mineralized.
“We then ground truth this satellite image by physically taking leaf
samples to the lab for analysis. That correlates back to the satellite
imagery. We also do a standard soil test as another layer on our
prescription map.”
Once information was pulled together, Carson started to reduce nitrogen
fertilizer by 80-100 lb. on the wheat. He hoped to maintain wheat
yields, but surprisingly they rose.
“We had been putting on too much nitrogen fertilizer, and that
contributes to lodging, which reduces yield. There’s also more disease
because of the lush growth.”
Carson added that his wheat yields did not increase solely because of
changes to his fertility management. In that same period, he also
started using insecticides and fungicides.
“Now that we have GPS and yield monitors, we have the technology to do
test strips.
“This lets us experiment with a lot of things we might not have tried
before. We’ve had some wheat fields that gave us an extra 22 bu. per
acre from just a single fungicide application, so there’s more to it
than just nitrogen management.”
While he originally looked at precision farming as a way to cut input
costs, Carson said there are other factors that motivate him.
“I think that in the next 10 years, fertilizer application will become
such a major environmental issue that it may be absolutely devastating
for those farmers who cannot account for all the nutrients they put
into their soil.”
