Sprayer Calibration Still Important 05/23 14:55
High-tech monitors have made it easier for farmers to ensure they are
applying the correct amount of chemicals on their fields, but an ag machinery
specialist says it is still important for farmers to manually calibrate their
By Russ Quinn
DTN Staff Reporter
OMAHA (DTN) -- Spraying crops is a bit like cooking a good meal: if you
don't include all the right ingredients in the correct amounts, you're likely
to end up with something that tastes bad, is a waste of time and effort and
ends up being a big mess.
Likewise, without taking the time to properly calibrate a sprayer and to
make sure it is spraying accurately, farmers very easily could be wasting
expensive crop protection material and exposing the environment to unnecessary
amounts of chemicals. Or, they could be spraying too little, potentially
allowing weeds to develop resistance to chemicals sprayed at a much
While he does not have any solid research, John Nowatzki, an ag machinery
specialist with North Dakota State University, figures less than half of
farmers calibrate their sprayers every year. He said some farmers still do not
take the time to calibrate their sprayers even though evidence shows that
calibration helps save money.
"Just last week I was talking to a guy up here in North Dakota, and he
estimated when he sprayed his crops last summer he was off about 10 percent,"
Nowatzki said. "While 10 percent does not seem like a lot to you and me, this
guy figured he wasted about $4,000 over-applying chemicals to his fields."
Over-application of chemicals can also have a negative effect on the
environment, especially on land with sandy soils. Chemicals can move more
freely into the groundwater in sandy soils compared to more clay-based soils.
While under-application of materials would appear to have fewer adverse
effects, this practice could lead to other problems in the longer term,
according to Nowatzki. Research has shown that weed resistance to herbicides
such as Roundup could be avoided if the full rate is applied and the weed is
Nowatzki said modern technology has come to the rescue of many farmers,
with high-tech spray-control monitors that can accurately spray the correct
amount of chemical. Those who do not calibrate their sprayers now have these
monitors as a backup, which makes spraying much easier today.
"These monitors have made it easier to spray more accurately, but farmers
should still calibrate their sprayers at least once a year," Nowatzki said.
"They also should make sure these monitors are working correctly."
DTN Agronomist Daniel Davidson agrees that chemical applicators should
not totally rely on spray monitors. Getting out and actually calibrating a
sprayer is still important, he said.
"These controls are very good and nice, but you cannot just hope these
controllers are accurate," Davidson said. "You have to make sure they are, and
the only way to do this is to get out there and calibrate the sprayer."
The easiest method for calibration is the ounces-equals-gallons method,
Nowatzki said. He suggested that before calibrating the sprayer, farmers should
make sure nozzle output is uniform, correct any nozzles that vary in flow by
more than 5 percent, and also check that the pressure gauge is reliable and the
pressure is properly set.
"If the nozzles are not uniform or the pressure is not properly set,
there is no need to calibrate because you are never going to get it right," he
For broadcast application calibration, the first step is an easy one:
determine the distance in inches between nozzles. The second step is to
determine the distance needed to equal 1/128 acre. This is determined with a
Calibration Distance Table.
The third step, Nowatzki said, is to mark this distance in a field you
will be spraying. Step four is to measure the time in seconds needed to drive
the required distance at normal operating speed with all equipment attached and
the spray tank half full. Step five is to collect the discharge from one nozzle
for the time measured in step four. The ounces collected from one nozzle equals
the application gallons per acre. This will show whether the sprayer is working
accurately, Nowatzki said.
Bob Worth, a Lake Benton, Minn., corn, soybean and spring wheat farmer,
does his fair share of spraying. He figures his sprayer covers about 7,000
acres a year with all the trips he makes across his farm.
Worth said he tries to calibrate his sprayer at the beginning of every
crop year, but he knows he has not been as good at calibrating since he bought
a spray controller.
"We try to do it every year, but I know over the last 10 years or so we
have really relied heavily on our spray monitor," Worth said. "It is pretty
amazing to be spraying with this controller. I know before we had it, I would
calibrate the sprayer every year. Now we just make sure the monitor is working
Worth, who farms with his son Jon, said they do replace their
1,200-gallon pull-type sprayer tip every other year. While there are a number
of nozzles on the market today, the Worths continue to use the basic flat fan
"Changing out the nozzles is something I know that is very important,"
Bob Worth said. "Volume and pressure is pretty much controlled now with the
monitor. We just have to make sure the tips are clean and ready to go."
Nowatzki agrees this is a good, simple practice to get into. Plugged
nozzles account for a lot of sprayer issues, he said.
"With new, modern sprayers, plugged spray nozzles are about the only
problem an operator is going to have since the pump and pressure gauges are new
and working correctly," he said.
Nowatzki said cleaning nozzles can be accomplished with an old
toothbrush, but since nozzles are not that expensive, he suggests farmers just
replace plugged nozzles with new ones. What he does not recommend farmers do is
blow out the nozzles with their mouths because it isn't safe to do.
Russ Quinn can be reached at firstname.lastname@example.org.
Copyright 2007 DTN. All rights reserved.