The problem with camera/spot-spray systems that nobody wants to talk about - Part 3

In the last two episodes we’ve discussed the problems associated with switching from side safety to single spot, that is halving of the rate (approximately) and understanding that where multiple nozzles engage in single spot mode the rate between them doubles (approximately).

Third and final problem is about discovering if your spray rate controller can actually be calibrated for single spot spraying at all.

As an example of something that can manage a spot sprite rate, let's look at the WEED-IT Quadro.

It is a complete spraying package with all the spray rate control functions. It calculates spot and blanket sprays with different formulae. For spot jobs, user inputs require the choice of nozzle angle and nozzle height ensuring the correct sized nozzle is selected.

Other camera and sensor based systems like the Bilberry variants, See & Spray or WeedSeeker provide messages to either the spray controller or the solenoids directly to turn nozzles on or off. That will require a level of integration with the spray rate controller if it is managing the spray job, or no communication at all other than recording flow and pressure if it is activating the nozzles directly.

Unless there is a camera integration with the spray controller that goes beyond turning nozzles on and off that includes the factors affecting single spot nozzle selection (angle and height) it is fair to assume the sprayer is doing a blanket rate. But how can you find out for sure?

A quick guide is just to look at the nozzle sizes. If a WEED-IT is doing 100 l/ha with 40° 04 red nozzles on 25 cm you would expect a sprayer on 50 cm to be using 80° 08 nozzles to apply the same volume.

I could spell out the math but that would be tedious. Suffice to say that 80° 04 red nozzles on 50 cm spacings, just cannot do 100 l/ha single spot at 20 kmh.

Therefore, if you are using smallish nozzles, 03, 04 or even 05 or 06 of 80° or 110° achieving 100 l/ha single spot is just not happening at least mathematically. I would take that as a very strong hint that your sprayer is managing your rate in blanket mode.

If you get instructions to double the rate I would call that a hint, and having instructions to set 3BAR pressure another. You can also look at the manufacturers instruction video’s and user manuals. Lastly if you cannot find somewhere to input the nozzle angle and height to your rate controller, that is telling you something too.

Based on all those observations it looks to me like Agrifac, JD and other systems with Raven spray rate controllers are still managing rates in blanket mode after you have switched to single spot.

I have done my research as best as I can. If my conclusions are incorrect, I will be happy to be informed otherwise.

What is the solution to the problem?

If you agree that you might have a problem, we’ve just gone through the math and derived an alternative controller setting for you based on the target zone. We’ve added a “Show controller rate” button that is designed to compensate for blanket rates and gives you a new number to plug in for single spot jobs.

Follow the link below and check it out. We'll be similarly upgrading the custom Apps shortly, so use the website version in the mean time.

Any questions, just call.

Dave

08 6102 5886