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Discussion Starter #1 (Edited)
Folks,

I had a nifty android app that calculated carrier volume and tractor speed for spraying, but it stopped working after a recent upgrade. So, I did some web research and came up with a simple spreadsheet that I thought others might find useful. Here it is:

Sprayer.PNG

The formulas are displayed in the cell to the right of the calculation. It isn't as sophisticated as other spreadsheets that I have seen, but it is easy to use and has given me good guidance. After all, spraying is an approximation.

Here is how it works:

Constants:

  • nozzle size: output in gallons/minute of your nozzles at the pressure that you intend to use. I didn't calibrate my nozzles. I just used the nominal value published by TeeJet and spray at their recommended pressure (40 psi.) Slight alterations in pressure have negligible impact on the output of the nozzle.
  • nozzle spacing - the distance between nozzles on your boom. (Interestingly, the formula doesn't use the boom width. That perplexed me for a while until I realized that the overall duration of the spray job is not part of the formula; only the speed of the rig. The speed is the same regardless of how many nozzles you have, but the more nozzles, the faster the job gets done.)
Calculations:

  • The Speed Calc lets you specify the gallons/acre that you want to apply and calculates the speed that will achieve it.
  • The GPA Calc lets you specify the speed that you want to travel, and calculates the gallons per acre that the specified speed will apply.
Examples:

  • I usually want to distribute about 2 qts of material/acre, in a volume between 20 and 30 gallons/acre, at a speed between 2-3 mph. So, I decide how much product/acre I want to apply, then play around with the two calculations until I find a speed and volume that I like.
  • For example, if I want to distribute 20 gallons/acre, then I need to maintain a speed of about 3 mph.
  • If I slow it down to 2.5 mph, then I will distribute about 24 gal/acre.
Disclaimer:

These two calculations work very well for me. I found them on a few .com and .edu sites. Double check against examples in your sprayer manual, past records, other spreadsheets, etc and proceed with caution until you are comfortable with them. I suggest taking a few checkpoints along the way to confirm that the actual application rate matches what you calculated so that you can make any interim adjustments​
 

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I appreciate the program you posted. I'd like to ask a related question even if it may seen as off topic.

I am ready to spray, and I'm supposed to be driving the tractor at 2.97 mph. I am planning to spray 5 acres, but it is fenced and cross-fenced into five 1 acre pastures so there are no long straight lines to drive. It's back and forth.

I have a 1025R so I know the top speeds in low and high range, and that's about it. The tractor has a cruise control, but no "return to speed" function like in a car.

Or, should I use the calculator so that I enter my top speed in low range, and calculate the mixture in the sprayer to match the flat out low range speed?

Anyone got any hints to share about how to drive at a constant speed? I had an idea about trying one of the cell phone speedometer apps, but haven't picked one yet to download.

Thanks.
 

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Discussion Starter #3
... I'm supposed to be driving the tractor at 2.97 mph. I am planning to spray 5 acres, but it is fenced and cross-fenced into five 1 acre pastures so there are no long straight lines to drive.

I have a 1025R so I know the top speeds in low and high range, and that's about it. The tractor has a cruise control, but no "return to speed" function like in a car.

Or, should I use the calculator so that I enter my top speed in low range, and calculate the mixture in the sprayer to match the flat out low range speed?

Anyone got any hints to share about how to drive at a constant speed? I had an idea about trying one of the cell phone speedometer apps, but haven't picked one yet to download.
I use an android cell phone app called "tractor speed" and it gives me good results. I use it to checkpoint my speed periodically, but I don't use it to continuously monitor my speed. I need to keep my focus on things like where the boom is (especially near obstacles), maintaining good parallel lines, and of course watching for surprise woodchuck holes that weren't there the last time. For me, trying to do all of that and watch the screen on my cell phone is too much. I didn't find the cruise control to be useful.

I have played with speeds between 2 and 4 mph, and lean towards a target average speed of 2.5 mph. At that speed, I can keep my eye out for potential hazards and even enjoy watching the barn swallows trying to drive me out of town!

I suggest setting your volume to spray your first paddock at 2 mph, then adjust for the second paddock based on how the first one went. By the time you get to the 5th one, you'll be a pro.
 

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While appreciate what you've done I am unable to tell the speed of my tractor. (don't own a cell phone).
I can easily maintain a constant speed, gear driven and I can adjust throttle for slight speed changes.

I have sprayed my fields (2-3 acres) several times using a Firmco 30 gal sprayer that I tow behind tractor.
I use a generic glyphosate which has a much higher concentration than round-up (41%).
I tend to mix it at the high end of the concentration (2 1/2-3 oz/gal).
All I do is look to wet the plants as I go along. I 'll speed up if it gets to the point its dripping off the leaves.
I do vary speed when I feel I need to go slower in thick or taller weeds or speed up when I hit relatively bare patches.
I have sprayed in times of heavy dew and relatively windy periods.
I have always had very good results.
EVERYTHING DIES.
Maybe I'm using too much but I feel that its better to error on the high end.
If I go too light and I don't kill everything I have to do it a second time using even more herbicide. This would be a waste and in the end I feel that 2 light applications use more herbicide than if I just applied one on the heavier end. Not to mention the time of applying and the biggest issue of not being able to plant seed for another 10 days or so if I have to reapply herbicide.
Glyphosate does not last in the soil so a "heavier" application only uses more herbicide. No real down side that I can see.

So while what you did is admirable I see it as an unnecessary complication.

I would advise anyone doing a small application (under 5 acres) as a hobby or non-commercial purpose to mix the herbicide on the high side of the mfgs recommendation, apply it so as to wet the leaves, avoid dripping/runoff, and apply when mfg recommends, that would be it.

My post is meant to just throw out another opinion of someone who has sprayed glyphosate several times over several years on 2-3 acres of land.
Take it for what its worth, I don't mean to diminish what you have done and how you might want to apply herbicide, just a simpler easier less complicated way of doing things.

I'm a simple man I like things to be simple:lol:
 

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Klunker, while going "heavier" on glyphosate may not cause lasting issues, doing the same with other herbicides can.

Go heavy with 2-4-D, you can burn your grass you want to keep

Go heavy with something with carryover (milestone for example) and the carry affects can last longer.
 

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I mean no disrespect towards Klunker personally but it's those those kind of general principles used by others in the past that resulted in a misuse of Ag chemical products. With that misuse came regulations making the products difficult to obtain by many who always used the products responsibly.
 
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