GrowNotes

Spray application manual

Module 12: GPS systems

12.9: Summary

Published 24 January 2025 | Last updated 20 January 2025

Investment in any technology has to be well researched. Whichever system the grower or spray applicator chooses, it must work well with the other equipment on- farm, now and into the future. 

There are a number of questions that growers and spray applicators should first ask themselves before purchasing a new auto-steer system for their sprayer. 

Age of machine

Depending on the age of the sprayer, is it worth spending money to retrofit new technology onto an ageing machine? Or are you better off upgrading your machine and getting auto-steer at the same time? 

Should you get auto-section control?

To answer this question you need to know if your boom is capable of section control, how wide it is and how many sections it has. In most cases, auto-section boom control payback period is very short and is a very good investment in any reasonable- sized rig with three or more sections. 

Warranty

Possible warranty issues can arise if, for example, you have plugged a third-party controller into your machine’s CAN bus. Check with the manufacturer before making changes and clearly identify who is responsible for each component of the system. 

What are the other systems on the farm?

If you have implemented a controlled-traffic farming (CTF) system, consideration needs to be given to the size of your sprayer, and its wheel and nozzle spacings, in relation to your other machinery. For example, ideally your sprayer and spreader

would be three times the width of your seeder (e.g. 9m seeder and 27m sprayer and spreader). Carefully note wheeltrack spacings, boom widths, nozzle spacings, and the like, as most will be in imperial measurements from the Unites States. 

Wheel spacings should also be matched, most commonly at 3m/120” (make sure that metric and imperial systems are not mixed together; use one or the other.) CTF considerations are important and different GPS systems can use quite different methods for steering control. Be aware that trying to get A/B lines from different auto- steer manufacturers to line up in a CTF/row crop system can be quite challenging and sometimes impossible. In this case, using the same GPS/GNSS manufacturer across the farm with a common base station will give the best results. 

Do you use contractors?

Contractors can often have different brands of guidance systems, and compatibility can be an issue. Specialist help is often needed to match boundaries and guidance lines. A pre-loaded data stick of farm/field boundaries and AB lines can save a lot of time and issues, especially when it comes to record keeping of spray activities; assuming the GPS/GNSS systems can align.