Spray application manual
31 January 2025
Module 14: Boom stability and height control
14.1: Introduction
Published 24 January 2025 | Last updated 20 January 2025
One of the most useful ways to increase the productivity of a sprayer is to use a wider boom. However, increasing productivity may come at the expense of efficacy if the nozzles cannot be maintained at the correct height above the target (or false target) to provide uniform coverage and minimise the potential for spray drift.
Too often spray operators need to raise the boom to stop the wings touching the ground, especially when spraying at higher speeds or on uneven surfaces, such as paddocks with depressions and contours.
Maintaining an appropriate boom height with wider booms often requires the addition of some form of height control, whether this is a manual system using touchdown wheels, an automatic system (hydraulic or electric hydraulic) using touchdown wheels, or an auto height system using sensors and hydraulic rams.
The ability of an auto height-control system to perform as intended will depend on the boom design, in particular the boom centre section.
This module outlines the importance of maintaining nozzle height, along with aspects the spray operator should consider about boom design to match their particular situation.
Benefits-of-height-control-systems
8 January 2025Benefits of boom height control systems. Another video from GRDC's Spray Application GROWNOTES™ series.
Bill Gordon: ""The decision to invest in height control for your boom sprayer largely depends on the width of the boom and the type of terrain you're working on.
In relatively flat country, the benefits may not be as significant. However, in areas with undulating terrain, height control systems can be invaluable for maintaining a consistent height above the target. This is critical for ensuring proper spray overlap and achieving effective canopy penetration with your droplets.
Height control systems come with different types of sensors, and their placement on the boom is crucial. Most setups include at least one sensor in the centre section and one on each side of the main boom. Some systems also feature sensors on the breakaway sections, allowing them to lift independently to maintain the correct height.
The height between the nozzle and the ground should be carefully monitored to ensure optimal performance. It's important to place the sensors in a position where they won't be affected by certain nozzle types, as interference can cause the system to misread and react unpredictably.
Height control systems can make a noticeable difference in maintaining boom stability and improving spray efficiency, particularly in challenging canopies. Ensuring they are correctly installed and calibrated is key to maximising their effectiveness.