GOODFIELD, Ill. — Managing nitrogen should be the concern of
“You may do what’s good for your farm in terms of nitrogen
management, but you should be concerned about what your neighbors are doing and
what farmers are doing 10 counties from your farm,” said Rachel Halbach,
agronomist with Hagie Manufacturing Co. “Because eventually regulation is
probably going to be part of what you have to base the programs around.”
There are several different forms of nitrogen, including
urea, ammonia, nitrates, nitrites and ammonium, Halbach said during the “Where
Technology Meets Dirt” Road Tour.
“We are most concerned with nitrates because they move the
most rapidly, and corn likes to take up and utilize nitrates,” she added.
Nitrates dissolve in water, and when water moves through
soil, the nitrates move, too.
“The nitrates may move out of the root zone of the corn, to
the ground water, to the creek and so forth,” Halbach said. “We like nitrates,
but they’re also our enemy because we can’t keep them where we need
There are several reasons to apply nitrogen to corn.
“Nitrogen is very important for nutrient uptake,” Halbach
explained. “When there is nitrogen deficiency, that inhibits the plant from
getting the rest of the nutrients it needs.”
Nitrogen impacts cell division and growth, and this really
comes into play in the fall, the agronomist said.
“If we have a nitrogen-deficient plant at the time of grain
fill, the plant will take the nitrogen out of the cells in the stalk and put it
into the grain,” she said. “That may mean lodging and standability issues in the
Leaching is one way nitrogen is lost.
“In a year with average rainfall, you will loose 15 to 50
pounds of nitrogen naturally due to leaching,” Halbach said. “It takes one pound
of nitrogen to produce one bushel of corn, so that’s 50 bushels of corn.”
Denitrification occurs in saturated soils and areas of the
field with standing water.
“The bacteria changes nitrates into gases, and the nitrogen
goes up into the atmosphere,” the agronomist said. “Within three days, you can
lose 10 percent of the nitrates and every day on top of that another 10
Halbach noted the importance to match the application of
nitrogen with the uptake of the plant to reduce the risk for loss.
“At V12, the plant has only used 40 percent of the total
nitrogen for the season,” she said. “The highest rainfall amounts are in April,
May and June, which are the highest risks for loss of nitrogen and corn isn’t
taking up nitrogen very quickly during this time.”
Nitrogen management will change from year to year because of
different weather conditions, Halbach said.
“We can become more efficient by spoon-feeding or
sidedressing nitrogen multiple times, and that takes time and more intensive
management,” she said. “But we’re reducing the risk for loss because we’re
putting smaller amounts on when the crop is able to take it up.”
The ability to apply nitrogen to the corn crop at the
appropriate time can be a challenge for farmers. If you don’t have a tool bar
and you rely on your local retailer to rent equipment, you may be the first or
the last on the list, Halbach said.
“And if you didn’t pre-pay or you have an unplanned nitrogen
application, the costs could be higher,” she said.
One option for farmers to use to evaluate the health of
their crops is the OptRx crop sensor.
“OptRx is short for optimum prescription, and the sensor is
mounted on a tool bar or sprayer to measure the crop health as you go through
the field,” explained Mike Olson, with Ag Leader Technology.
The OptRx sensor determines a vegetative index that includes
the biomass and health of the crop, Olson said.
“We can apply nitrogen based on the health of the crop,” he
said. “In areas that are struggling, we put more nitrogen down.”
Olson stressed that the sensors are not a silver bullet.
“If your P and K levels aren’t right, the sensors will
detect the stress and nitrogen will be put down, but there could be other
issues,” he noted.
“We ran the sensors across the field at V5 stage, and we can
pretty much predict the yields,” he said. “The losses and stresses at V5 carried
all the way through to harvest, so that gives us an opportunity to improve that
situation by hitting the crop with sidedressing nitrogen.”
Ag Leader recommends using the OptRx sensors when the corn
crop is at the V5 stage or about one-foot tall.
“That’s when we have enough canopy to be able to measure the
crop and to be able to see what it’s doing,” Olson explained. “Prior to V5, we
get a lot of dirt and background noise in the sensor data.”
The operator of the applicator has total control of the
amount of nitrogen applied in a field.
“You are in charge,” Olson stressed. “You can enter a
minimum rate and a maximum rate you want to apply.”
Calibrating the OptRx sensor is important just like any
other sensor system.
“You can calibrate the sensors anywhere in the field, so go
to a good part of the field and base your calibration off that part of the
field,” Olson advised.
“As long as the different hybrids have similar
characteristics like the same maturity rates and planted in a similar timeframe
so they are in the same growth stage, you don’t have to do different
calibrations for different hybrids,” he said.
However, Olson added, if the corn is in different growth
stages, recalibration will be necessary.
“A three-sensor system from Ag Leader will run about
$11,000, but don’t let the price scare you,” he said. “With $20 per acre more
profit, it only takes 525 acres to pay for the sensors, so you can pay for them
For more information about Ag Leader Technology, see