Hello. My name is Mark Renz. I'm with the University of Wisconsin-Madison. And I'm
an extension specialist. I'm here to talk to you today about how to calibrate a sprayer and this is
where we're using an atv or utv sprayer for natural areas or other hard to reach areas.
This is something that isn't done quite often, but it really can have benefits. And we really
recommend trying to calibrate multiple times a year if possible. There's lots of other videos
and other assistance on how to do this, but it gets really complicated with equations and
other things. We're really going to try and simplify it for you in this video, where all
you need is something to measure your output, tape measure to measure the width of your boom,
and a timer and a smartphone to help with conversions. Now calibration is really important
because you want to know the right amount that you're applying per unit area. We're going to
calculate gallons per acre of output of this material of this sprayer. It's really important
so we can understand how much is putting out so we can help us when we know how much to mix
and ensure we're putting out the right amount of product per acre. Realize if we're putting
too little out it might not perform as well as we would like, and if we're putting too much out
it might injure some of the species that we think are tolerant to this. A great example is milestone
or amino pyralid. If we go above the label rate we can injure those grasses which are typically safe.
And most importantly it's the law. We're legally required to apply specific amounts
of these products per acre and if we go over that we're breaking the law. Some labels will
have percent solutions to help with mixes but still we're required to know how much
per unit area we're putting out. And so that's what we're going to go through today.
We're going to go through three simple steps on what you need to know in order to make this
calculation. The first step is we're going to know what the width of our spray boom is here.
The second step is we're going to calculate how much is being put out by each nozzle or
for that whole spray boom. And then the final one, which is actually harder than you think, because
we're going to show you how to estimate the speed or how fast you're traveling when you're making
those applications. And then we're going to bring those all together in calculations to estimate
the output of the sprayer in gallons per acre and that will help you with all of the stuff that we
just talked about. So let's get going and calculate. First step one. Okay i'm here with Tom Wise with
the Nature Conservancy and we're going to do the first step in determining what the spray width is
that we're actually spraying realize we have seven nozzles here and they're all about 20 inches apart
and realize that these nozzles have to overlap, so in order for us to determine and measure the
effective spray width, we have to measure out half the distance from the edge of that last
nozzle. So Tom's going to help me here with and put that sprayer out and we're going to measure
all the way over. And what we see is the effective spray width is 144 inches or 12 feet. That's the
important first piece of information to use in this calculation. Okay the next step is a
little bit more tricky but it's actually not that bad really. What we're going to use in this case
is a graduated cylinder and a timer. I'm going to use my smartphone and what we're going
to do is we're going to determine how much each nozzle is putting out in a 10 second time frame.
So we have it running and going,Ii'm going to start my timer and put it underneath and for 10 seconds.
And when that 10 seconds is up I'm going to pull it out and estimate how much that volume is.
So it's a good idea to check multiple nozzles just to make sure that they're all working and
not worn or clogged. They should be within five percent to make sure you have a good spray pattern.
Okay you can see that's pretty easy. We ended up in this case with 130 milliliters in 10 seconds.
Now we're gonna repeat that on all these nozzles to come up with how much each one is putting out
and hopefully it's within five percent and that'll allow us to make our next step in the calculation.
Okay so the third and final important piece of information is the the speed that we're
traveling. And a lot of these have speedometers, we really can't trust them. So what you want to do is
try and practice the speed you think you're going to travel in your in your area, and then
you want to measure out a specific length so we can determine what that speed is. So what I've
done here is we've measured out 50 feet. And what i'm going to do is i'm going to have
Tom drive at his expected speed and we're going to actually measure the distance the speed traveled.
And we're going to measure it in seconds per 50 feet. So we're going to have Tom go
ahead and go and I'm going to hit start when he hits the the zero point.
As you can see it took us almost nine seconds to travel 50 feet. It's always a good idea to do
this a couple times to make sure that your speed is accurate and it's going to be the appropriate
speed you want to take in that terrain which is okay. So now that we've completed our three steps
what we found out is the width of this boom is 12 feet we've also determined the output of this
spray room the each nozzle was giving us between 150 and 160 milliliters in 10 seconds, if you add
up the number of milliliters across those seven nozzles that come and divide that by 10 that comes
out to 108.5 milliliters per second. And then we measured the distance traveled and the time it
took and we found that in nine seconds we were able to travel 50 feet, that's 0.18 seconds per
feet. Now the magic is we need to use all of that information to convert it into gallons per acre.
We're going to show you in another video how to do that, but using our calculations that comes out
to a little over 17 gallons per acre, which is right about where we typically want to be, between 15 and
30 gallons per acre for this spraying unit. So as you can see this approach is pretty simple. It uses
technology to help us get an understanding of what the output of these atv and utv
sprayers are, so we can better understand how much pesticide we're putting out on the landscape and
make sure we're applying it safely and correctly to get our desired results. We'll have a lot more
information and links to other resources in this in this video. So good luck and happy spraying.